Methods for treating abnormal growths in the body using a flow reducing implant

ABSTRACT

Methods of using flow reducing implants for treatment of abnormal growths in the body are described. In embodiments of the claimed subject matter, a source blood vessel feeding the abnormal growth is first determined, and a flow reducing implant is then inserted into the source blood vessel to reduce the blood flow through the source blood vessel. The flow reducing implant includes at least one flared section for contacting a blood vessel wall, and at least one narrowed section defining a flow passage. Anchor tabs that lie generally in a plane of the flared section may also be employed.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/491,976 filed on Oct. 8, 2004 (now abandoned), filed as PCTapplication No. PCT/IL2002/000805 on Oct. 3, 2002, which designates theU.S. and which published in English, which is a continuation-in-part ofPCT application No. PCT/IL2001/000284 filed on Mar. 27, 2001, whichdesignates the U.S. and which published in English, which is acontinuation-in-part of U.S. application Ser. No. 09/534,968 filed Mar.27, 2000, the technical disclosure of all of which are incorporatedherein by reference. This application also claims the priority of Israelapplication Nos. 145750 filed Oct. 4, 2001 and 151162 filed Aug. 8,2002, the technical disclosure of all of which are incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention relates to implants for reducing flow throughbodily conduits, for example, blood vessels.

BACKGROUND OF TAE INVENTION

The heart pumps blood through the body. The heart itself is fed bycoronary arteries that end at capillaries. The capillaries are drainedby a network of coronary veins, that (typically) flow into a vein knownas the coronary sinus. The coronary sinus is a short, large diametervein that is substantially contiguous with a right atrium, the atriumthat collects all venous blood from the body.

Occlusion of coronary arteries is a leading cause of death, especiallysudden death, in what is commonly called a “heart attack”. When bloodflow to a portion of the heart is suddenly stopped, the portion becomesischemic and its electrical activity is disrupted. As the activity ofthe heart is mediated by electrical signal propagation, such disruptiontypically propagates to the rest of the heart, disorganizes the heart'sactivation and causes the heart output to be reduced drastically, whichleads to ischemia and death of the brain. In addition, the disorganizedactivity often damages the heart beyond what was caused directly by theblockage.

If a patient survives the direct effects of the heart attack, the damageto the heart may predispose the patient to future electrical disordersand/or may significantly reduce the cardiac output, thus reducingquality of life and life expectancy.

Angina pectoris is a chronic or semi-chronic condition that, while notlife-threatening, significantly reduces quality of life. In general, theheart responds to increased demand by working harder, requiring morecoronary blood flow. When coronary arteries are stenosed or occluded,the increased blood flow cannot be provided, and pain, caused by theresulting ischemia, is produced.

The heart has natural mechanisms to overcome stenosis in coronaryarteries. One such mechanism is angiogenesis, in which new arteries arecreated, for bypassing the stenosis.

Since angiogenesis sometimes does not occur naturally, variousprocedures have been suggested to encourage it. For exampleTrans-Myocardial Revascularization (TMR), is a process in which multipleholes are drilled in the heart, with the intent of causing new vesselsto be created.

Beck, in “The Surgical Management of Coronary Artery Disease:Background, Rationale, Clinical Experience” by C. S. Beck and B. L.Brofman, 1956, by the American College of Physicians in Annals ofInternal Medicine Vol. 45, No. 6, December 1956 and in “Long TermInfluence of the Beck Operation for Coronary Heart Disease”, by B. L.Brofman in the American Journal of Cardiology August 1960, thedisclosures of which are incorporated herein by reference, performedopen chest surgery in which a coronary sinus vein was restricted, by anexternal suture. After a few months, coronary blood supply apparentlyimproved. However, this method has fallen in disfavor, in part possiblydue to the need to open the chest and lift up the heart, to reach thecoronary sinus vein.

A standard treatment of stenosed arteries is inserting a stent into theartery, at the stenosed point. The stent, for example a metal coil ormesh, is expanded to have an inner diameter similar to that of theoriginal stenosed blood vessel. If many and/or elongated stenoses arepresent, it is not common to implant multiple stents. Instead, a bypassprocedure, in which a conduit is used to bypass the stenoses, isperformed.

U.S. Pat. No. 5,618,301, the disclosure of which is incorporated hereinby reference, describes a stent-like device for reducing the diameter ofa body conduit. What is described is an open mesh stent that can beinserted in a channel created by a TIPS (Trans-Jugular Intra-HepaticPortal-Systemic Shunt) procedure, to reduce the blood flow rate throughthe channel, In order to ensure the flow diameter is reduced and preventflow through the open mesh, a plurality of thromobogentic threads areprovided on the outside of the mesh. However, as can be appreciated,intentionally forming thrombosis in most any part of the vascularsystem, and especially near the heart, can lead to propagatingcoagulation or floating thromboses, which are potentially fatal.

SUMMARY OF THE INVENTION

An aspect of some embodiments of the invention relates to an anchor fora flow reducing implants adapted for insertion into a blood vessel. Inan exemplary embodiment of the invention, one or more tabs are providedon a circumference of the reducing implant. In an exemplary embodimentof the invention, these tabs engage the blood vessel wall if the implantmoves axially relative to the blood vessel and are, for example,extended axially towards or away from the reducing implant.Alternatively or additionally, these tabs prevent rotational motion. Insome embodiments of the invention, the tabs are not exactly aligned withthe axis of the blood vessel, for example, being pointed towards thewall of the blood vessel or being angled relative to the axis, but inthe plane of the blood vessel wall. In an exemplary embodiment of theinvention, the tabs are elastically pre-stressed to extend in thedesired direction. Alternatively, the tabs are formed out of a samesheet material as the reducing implant. and the implant is of a typewhere one portion is narrowed and another is flared. The tabs areattached to the flared portion and cut away from the narrowed portion,so that when the reducing implant is deployed the tabs continue in asame plane as the flared portion.

Optionally, the tabs dig into the blood vessel wall and/or are adaptedto encourage tissue ingrowth or other biological or physical anchoringeffects.

An aspect of some embodiments of the invention relates to varying slitgeometry in a reducing implant to effect a control over the expandedshape of the reducer. In an exemplary embodiment, a slit-type flowreducing implant comprises a matrix, for example a sheet of metal intowhich one or more slits are cut. The one or more slits serve to governthe contour of an expanded configuration of the slit-type flow reducingimplant. In an exemplary embodiment, the slit-type reducing implant isdelivered to the implantation site in a contracted size, for examplewithin a delivery sheath, and expanded to is final configuration at thedeployment site. Said expansion, for example, employs the use of aballoon expansion catheter, for example, that exerts appropriateexpansion force on the walls of the lumen of the flow reducing implantso that the slits expand and the implant attains its finalconfiguration.

In an exemplary embodiment of the invention, the one or more narrowedsections are non-expandable, expand less and/or require a greater forceto cause them to expand, as compared to flared sections. In this manner,using expansion force provided by a standard balloon catheter thatexpands within the lumen of the flow reducing implant, the implantachieves its final configuration comprising at least one flared sectionand at least one narrowed section.

Alternatively or additionally, at least a portion the flow reducingimplant is self expanding (e.g., shape-memory, elastic or superelastic). Optionally, the flow reducing implant comprises materials witha shape memory so the flow reducing implant automatically attains adesired shape following release, for example, from a delivery catheterinto the coronary sinus.

In an exemplary embodiment of the invention, the flow reducing implantcomprises a rim, for example along the flared edge, that is constructedto be more difficult to expand (for plastic) or expand less (forself-expanding) than portions of the flow reducing implant just insidethe rim.

In an exemplary embodiment, the slits of the slit-type reducing implantcan be varied in width, thickness (of surrounding material) density,length and/or orientation thereby providing specific expandedconfigurations to the implant (e.g., self-expanding or activelyexpanded). In this manner, flow reducing implants providing differentconfigurations, for example, filling the flow reduction needs of avariety of environments in the body, can be provided. Alternatively oradditionally, the variations may affect the order in which parts expandand/or the response to an external pressure, thus possibly allowingvarious effects to be achieved from a single reducing implant.Alternatively or additionally, the variations may affect the amount ofblood flow through the reducer walls.

For example, one or more slits may be provided in the flared section ofthe flow reducing implant walls that are oriented transverse, obliqueand/or longitudinal to the flow reducing implant flow passage. As aresult, the flared section expands to a specific contour, for example,with a gradual slope, to fit a specific blood vessel and/or provide aspatial blood flow profile. Optionally, the slits governing theconfiguration of the flow reducing implant are arranged so that theimplant achieves a configuration that is asymmetric.

In an exemplary embodiment, a flow reducing implant comprises a smoothedge along its rim, defined, for example by the pattern of slits. Thesmooth edge, for example, reduces irritation to the tissue, for exampleto venous tissue that is often more delicate than arterial walls.

In an exemplary embodiment, a mesh-type flow reducing implant comprisesa woven open material, for example of metal and/or plastic fibers, usingmethods well known in the art.

In an exemplary embodiment, a mesh-type or woven flow reducing implantcomprises a covering that restricts blood flow through the wall of thenarrow area of the flow reducing implant while one or more portions ofthe flared sections are not covered. Optionally, at least one portion ofone or more of the uncovered flared section is adapted to interface withthe blood vessel wall, for example anchoring the implant in the bloodvessel wall. Optionally, the flow reducing implant is coated with aflexible coating (inside and/or out) and/or defines a densely woven meshpattern and/or slit pattern, that prevents or reduces blood flow throughthe flow reducing implant surface, for example, forcing at least 40%,60%, 80%, 90% or any smaller, greater or intermediate flow percentage tobe through an axial lumen defined by said flow reducing implant. In anexemplary embodiment of the invention, the dense mesh and/or dense slitsfill at least 30%, 40%, 60%, 70%, 80% or any greater, smaller orintermediate percentage of a surface of the flow reducing implant.

Some features described for a woven mesh-type reducing implant may beapplied to a slit-type reducing implant and embodiments described for aslit-type reducing implant may be applied to a mesh-type reducingimplant. In addition, an aspect of some embodiments includes structuralimprovement that are less specific to the type of implant material.

In an exemplary embodiment of the invention, the reducer is formed of athick material, possibly with a constant outer diameter, with the flaredout portions being formed by thinning the inside layer of the reducer.The reducer may be, for example expanding or it may be simply crimped,so that it expands uniformly along its length, like a stmt.Alternatively or additionally, this structure is used to assist indifferentiating the inner diameters of different parts of an expandingreducer.

An aspect of some embodiments of the invention relates to a flowreducing implant that may be modified following implantation in a bloodvessel, for example a coronary sinus and/or artery. For example, suchmodifications may be made in the size of its flared and/or narrowedsections, shape or configuration and/or in situ location.

In an exemplary embodiment of the invention, the blood flow exiting aflow reducing implant is modified by inserting an insert into the narrowand/or flared sections of the flow reducing implant. In an exemplaryembodiment of the invention, the inserted body comprises a funnel with avariable diameter, such diameter being determined by the diameter ofsurrounding implant. For example, as the in variable insert is pressedinto a flared section with a gradual slope, the size of the funnelinsert and/or hole at its apex, is reduced, thereby reducing the bloodflow through the flow reducing implant.

Alternatively or additionally, the flow reducing implant includes a setof apertures on its narrow section and/or a set of hooks or otherengagable elements adapted to be engaged by a catheter that is insertedinto the reducer. The catheter engages the flow reducing implant andpulls in radially on the walls, for example, of the narrowed section, toreduce its diameter.

Alternatively or additionally, one or more rings or cords, is providedaround some or all of the circumference of the narrowing (or other partof the reducer implant). These rings may prevent expansion.Alternatively or additionally, when sufficient pressure is applied, therings (or cord) may tear and greater expansion (e.g., to the limitsdefined by the device or a next ring, under the applied pressure, areachieved). Alternatively or additionally, the ring is elastic and whensufficient pressure is applied, the implant expands plastically, untilthe point where the applied pressure is smaller than the sum of theresistance of the implant and the resistance of the ring. Once thepressure is removed, the force applied by the ring is not enough tocollapse the implant, for example, due to the rigidity of the implant ordue to the change in geometry of the implant.

Alternatively or additionally to providing multiple rings, each with adifferent breaking point, a belt with multiple stop points may beprovided. For example, each time pressure is increased, the belt mayjump one stop, thereby allowing some expansion of the narrowing. Thestop points may, for example, offer equal or increasing resistance tojumping.

Optionally, when a cord is provided, it is weaved into the reducerimplant, possibly serving to block flow through the implant walladditionally or alternatively to determining its geometry. Optionally,the length of cord can be varied by a physician, for example beforeimplantation, or after, for example by engaging the cord and pulling itto reduce the reducing implant narrow diameter.

In some embodiments of the invention, the flow reducing implant wall atthe narrowing is formed by overlapping scales (e.g., by “U” shaped cutscut out of the implant wall). As the cord expands, the edges on the atleast one wall of the cord-type flow reducing implant move in relationto each other, thereby providing one or more expansion diameters. In anexemplary embodiment of the invention, the original diameter of thenarrowed section of the implant is greater than that of the deployeddevice. Providing such “U” shaped cuts (e.g., with the tongue of the “U”pointing perpendicular to the axis), allows the narrowed section to becompressed, whereby the “U” tongues overlap like scales, inside thelumen of the implant and/or outside of the lumen.

Alternatively or additionally, the implant may be formed of a rolledsheet material, with overlap. As the implant is expanded, the overlapbetween parts of the sheet is reduced. Optionally, the initial overlapis set by a cord.

In an exemplary embodiment, a plurality of rings are provided and arespaced axially apart from each other, limiting the expansion of thesection between them. A plurality of such rings may also be used todefine the expanded geometry to be other than a simple, symmetricnarrowing. For example to define the slope of the narrowing.

In an exemplary embodiment of the invention, the ring is an inflatableballoon, for example mounted on the outside of the reducing implant orformed by the surfaces of the implant. In an exemplary embodiment of theinvention, as the balloon is inflated more, the reducing implant innerdiameter lessens. In an exemplary embodiment of the invention, theballoon is inflated outside the body. Alternatively or additionally, itis inflated during implantation. Alternatively or additionally, theballoon is inflated after the fact, for example by guiding a needlecatheter to the implant, piecing the balloon with the needle andinjecting a fluid through the needle. Optionally, the balloon is backedby a tough layer, for example kevlar to prevent over penetration of theneedle. Alternatively or additionally, the needle catheter is shaped tomatch the narrowing geometry and thus ensure correct placement.Alternatively or additionally, the needle length is limited by a stop soit cannot penetrate far past the reducer implant wall.

Alternatively or additionally, to an inflated balloon, the balloon maybe self inflating, for example being formed of (or filled with) amaterial that expands under moist conditions.

In an exemplary embodiment of the invention, the reducer is surroundedby an active band, for example including a motor which is activated byexternal signals (e.g., RF ultrasound or magnetic fields) to shorten orlengthen the effective length of the band.

Alternatively or additionally to providing a mechanism for changing anarrowing, other flow control methods may be used. In one example, oneor more flaps or ribbons selectively extend into the lumen of thereducing implant. Such ribbons or flaps may be selectively torn and/orbent flat to the vessel wall, for example during or after deployment.Alternatively or additionally, the reducing implant may include twocoaxial reducing implants, with slots that can be selectively aligned.If the slots are misalign, flow through the walls of the reducingimplants is reduced. If the slots are aligned, such flow is increased.The reducing implants may be selected to be alignable over their entirelength. Alternatively, for example if an hour-glass shaped reducingimplant is used, one flared section may be designed to be mis-alignedwhen the other flared section is aligned. Optionally, this embodiment isused to select if blood should flow into or out of the space between theimplant and the blood wall, possibly affecting collapse of the vesselwall on the implant. The two reducing implants are, in some embodimentsof the invention aligned inside the body. Alternatively or additionally,they are aligned outside the body. Optionally, the inner reducingimplant is adapted to be mounted inside a reducing implant, rather thana vessel wall, for example, including short hard radial anchors, ratherthan a soft, smooth coating on its edge.

An aspect of some embodiments of the invention relates to a balloonadapted to be removed from a flow reducing implant with a narrowing,through the narrowing and after inflation. In an exemplary embodiment ofthe invention, the balloon or an outer sheath provided with the ballooncomprises a plurality of somewhat flexible wires, which, when retractedthrough the narrowing and/or through an aperture defined in a deliverycatheter, compress together, thereby radially compressing the balloon.Alternatively or additionally, the wires are not axially arranged, forexample being spirally arranged, so that when the balloon deflates, theballoon will twist closed.

An aspect of some embodiments of the invention relates to a flowreducing graft-stent comprising a stent body, which may or may notdefine a narrowed portion and a graft section that is mounted on thestent, for example on its outside or with the stent embedded in thegraft, wherein the graft does define a narrowing, for example the graftbeing generally cone shaped. The graft section is optionally held openusing one or more stiffening elements and/or a ring at its narrowedsection. Optionally, the graft is impervious to blood flow.

An aspect of some embodiments of the invention relates to a reducingimplant mounted inside a support element, for example a stent, a graftor a stent graft. Optionally, this prevents damage of the surroundingvessel by the reducing implant. Alternatively or additionally, thisallows the reducing implant to be more easily removed.

An aspect of some embodiments of the invention relates to reducing avessel diameter using an external element, such as a band or clip. In anexemplary embodiment of the invention, a band is inserted outside theblood vessel and tightened, to reduce the diameter of a narrow and/or awide section of the flow reducing implant. Such a band may be left inthe body, or removed (e.g., be part of a tool), for example, if the flowreducing implant is plastically deformed by the tool. Alternatively oradditionally, the band is used to force a collapsing of the vessel onthe flow reducing implant, for example is such collapsing did not occurby itself.

An aspect of some embodiments of the invention relates to using areducing implant in parts of the body other than the coronary veinsand/or coronary sinus. In one example, a flow reducing implant is usedto reduce flow through one or more veins in the leg resulting inredistribution of blood in the leg and/or triggering of angiogenesis orexpansion of existing blood vessels. In another example, a flow reducingimplant is used to reduce arterial blood flow to abnormal growths (e.g.,tumors), such as growths in the uterus and/or growths in the Liver. Aparticular property of the liver and the uterus is that these organsreceive blood from at least two different sources, while the growths inthese organs often receive blood from only one of the sources. Inaddition, the normal tissue may be able to weather a sharp reduction inblood, while a tumor growth may not.

There is thus provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

a flared section adapted to contact a blood vessel wall;

at least one narrowed section continuous with said flared section; and

at least one anchor tab that lies generally in a plane of said flaredsection. Optionally, said implant is formed of a sheet material andwherein said tab is attached to a portion of said flared section that isgenerally parallel to a wall of said blood vessel, Alternatively oradditionally, said anchor tab points axially. Alternatively oradditionally, said anchor tab points towards said narrowed section.Alternatively or additionally, the implant comprises at least twoopposing anchor tabs. Alternatively or additionally, the implantcomprises at least two flared sections, each one with at least oneanchor tab.

In an exemplary embodiment of the invention, said implant is plasticallydeformed to said configuration. Alternatively, said implant self-deformsto said configuration.

In an exemplary embodiment of the invention, said anchor tabs are bluntenough to generally prevent damage to said blood vessel.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

a flared section adapted to contact a blood vessel wall;

at least one narrowed section continuous with said flared section andadapted to be narrowed after implantation. Optionally, the implantcomprises an external ribbon adapted to selectively increasinglyconstrain said narrowing. Optionally, the implant comprises an impulseradapted to receive signals from outside the body and constrain saidribbon in response.

In an exemplary embodiment of the invention, said ribbon is expandable.Alternatively or additionally, said ribbon is inflatable.

In an exemplary embodiment of the invention, said ribbon is self-expandsby absorption.

In an exemplary embodiment of the invention, said ribbon is tearable.

In an exemplary embodiment of the invention, said narrowed sectioncomprises a plurality of engagement points adapted to be engaged, forradial constriction, by a catheter with matching engagers. Alternativelyor additionally, said narrowed section is adapted to be selectivelywidened after implantation.

In an exemplary embodiment of the invention, said narrowed section isinflatable.

In an exemplary embodiment of the invention, said narrowed section isexpandable in thickness.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

a flared section adapted to contact a blood vessel wall;

at least one narrowed section continuous with said flared section; and

at least ribbon coupled to said narrowed section and adapted to defineat least two discrete expansion states of said narrowed section.Optionally, said at least one ribbon comprises a tearable ribbon.Alternatively or additionally, said at least one ribbon comprises aribbon with a sliding clasp and a plurality of stop positions definedthereon. Alternatively or additionally, said at least one ribboncomprises a plurality of ribbons, being different in at least one ofinitial diameter, tear strength and final diameter. Alternatively oradditionally, said at least one ribbon comprises a sated ribbon having afirst diameter and a second diameter set by said slits being closed orexpanded. Alternatively or additionally, said at least one ribboncomprises a cord woven into said narrowed section.

In an exemplary embodiment of the invention, said at least one ribbonlies outside of said narrowed section.

In an exemplary embodiment of the invention, said at least one ribbon isbiodegradable.

In an exemplary embodiment of the invention, said at least one ribbonblocks flow through a wall of said narrowed section.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

a flared section adapted to contact a blood vessel wall;

at least one narrowed section continuous with said flared section,

wherein said implant comprises at least one overlapping section, whoseoverlap changes when said narrowed section is expanded. Optionally, saidoverlap comprises a plurality of overlapping cut-outs of said implant.Alternatively or additionally, said overlap comprises an overlap ofsubstantially an entire length of said implant.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

a stent-like element adapted to anchor in a tubular blood vessel; and

a flexible cone-shaped nozzle mounted on said stent, said cone shapednozzle defining a narrowing that substantially reduces a cross-sectionof blood flow through said sent-like element. Optionally, said nozzlecomprises at least one stiffener.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

an open weave mesh that does not substantially impede blood flow,therethrough; and

a layer of graft material mounted on said mesh and defining a narrowedlumen for blood flow therethrough. Optionally, said open weave meshforms an hourglass shape when expanded in said graft material layer.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

a flared section adapted to contact a blood vessel wall;

at least one narrowed section continuous with said flared section,

wherein said implant is defined by a sheet material with slots andwherein a width of said slots varies over the implant to control anexpanded geometry of said implant.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant, comprising:

a flared section adapted to contact a blood vessel wall;

at least one narrowed section continuous with said flared section,

wherein said implant is defined by a sheet material with slots andwherein said slots are arranged in axial lines and wherein saidalternating lines have different lengths of slots at a same axialposition.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant for reducing blood flow in a bloodvessel, comprising:

a body having a cross sectional dimension; and

a restricting element that at least partially encircles a blood vessel.Optionally, said element pierces said blood vessel. Alternatively oradditionally, said element comprises a tack or a suture. Alternativelyor additionally, said element comprises a band. Optionally, said bandcomprises a ratchet mechanism that maintains it in position in respectto said vessel. Alternatively or additionally, said band comprises aplurality of expandable slits.

In an exemplary embodiment of the invention, said element comprises oneof a clip, clasp and vise. Alternatively or additionally, said elementcomprises a spiral.

In an exemplary embodiment of the invention, said element comprises anexpandable material. Optionally, said element is adapted to expand byexpansion pressure from the interior of said blood vessel. Optionally,said implant is adapted to expand in response to expansion pressure of aballoon catheter.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of treating abnormal growth: in the body,comprising:

determining a source artery for the growth; and

inserting a flow reducing implant with an adjustable configuration intothe determined artery, such that flow to the growth is reduced.Optionally, said growth is extant in an organ that is fed from multiplesource arteries. Alternatively or additionally, said growth is fed by asingle source artery. Alternatively or additionally, said growthcomprises a leiomyoma. Alternatively or additionally, said growthcomprises a malignant tumor. Optionally, said tumor is a liver tumor.Alternatively or additionally, said tumor is an encapsulated tumor.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of treating blood flow problems in a limb,comprising:

identifying at least one vein that if flow in the vein is reduced isexpected to reduce the blood flow problem; and

inserting a flow reducing implant into the determined vein. Optionally,said vein is a deep vein. Alternatively, said vein is a surface vein.

There is also provided in accordance with an exemplary embodiment of theinvention, a flow reducing implant comprising:

an outer generally tubular section adapted to be inserted in a bloodvessel; and

an insert adapted to lodge in said tubular section, said insert designedto reduce blood flow passing through the blood vessel. Optionally, saidgenerally tubular section is designed to reduce blood flow passingtherethrough. Alternatively or additionally, said insert comprises afunnel shaped insert. Alternatively or additionally, said generallytubular section is designed to not reduce blood flow passingtherethrough. Alternatively or additionally, said generally tubularsection comprises a plurality of opening in its wall and wherein saidinsert comprises a plurality of opening in its wall. Optionally, saidinsert and said tubular section are rotationally alignable to modify analignment of said pluralities of openings with each other.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of reducing flow in a blood vessel, comprising:

selecting a location in the vessel to narrow;

inserting a flow reducing implant into the blood vessel at the location;and

mounting a restricting element on said vessel at the location and oversaid flow reducing implant. Optionally, said restricting element reducesan inner diameter of said flow reducing implant. Optionally, said methodcomprises removing said restricting element.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the invention will be described withreference to the following description of exemplary embodiments, inconjunction with the figures. The figures are generally not shown toscale and any measurements are only meant to be exemplary and notnecessarily limiting. In the figures, identical structures, elements orparts that appear in more than one figure are preferably labeled with asame or similar number in all the figures in which they appear, inwhich:

FIG. 1 is a schematic showing of a flow reducing implant installed in acoronary sinus vein, in accordance with an exemplary embodiment of theinvention;

FIG. 2 is a schematic side view of a flow reducing implant, inaccordance with an exemplary embodiment of the invention;

FIGS. 3A-3B are plan layouts of a slit-type flow reducing implant, inaccordance with an exemplary embodiment of the invention;

FIG. 3C is an isometric vies of the flow reducing implant of FIG. 3Amounted on a balloon catheter delivery system, in accordance with anexemplary embodiment of the invention;

FIGS. 4A-4B are plan layouts of a slit-type flow reducing implant, inaccordance with an exemplary embodiment of the invention;

FIGS. 4C-4D are a plan layout and isometric view, respectively, of aslit-type flow reducing implant with a smooth rim, in accordance with anexemplary embodiment of the invention;

FIG. 5 is a vascular path to a coronary sinus, in accordance with anexemplary embodiment of the invention;

FIGS. 6A-6C are three exemplary vise embodiments that reduce flowthrough a blood vessel, in accordance with an exemplary embodiment ofthe invention;

FIGS. 6D-6F show three exemplary clamp embodiments that reduce bloodflow through vessel 1002, in accordance with exemplary embodiments ofthe invention

FIG. 6G illustrates an exemplary endoscopic tool for releasing a bloodvessel reducing clip, in accordance with an exemplary embodiment of theinvention;

FIGS. 7A and 7B are a plan view and an isometric view of a flow reducingimplant embodiment with anchors, in accordance with an exemplaryembodiment of the invention;

FIG. 8A is a portion of a plan layout of a section of a flow reducingimplant with selective narrowing control, in accordance with anexemplary embodiment of the invention;

FIG. 8B is a side cross-sectional view of a flow reducing implant and amatching catheter for reducing a diameter of the flow reducing implant,in accordance with an exemplary embodiment of the invention;

FIG. 8C is a two-part flow reducing implant, in accordance with anexemplary embodiment of the invention;

FIG. 8D is a flow reducing implant and insert, in accordance with anexemplary embodiment of the invention;

FIG. 8E is an isometric view of a dual layer flow reducing implant, inaccordance with an exemplary embodiment of the invention;

FIGS. 9A-9G are embodiments of flow reducing implant, in accordance withexemplary embodiments of the invention;

FIGS. 10A-10B are an isometric view and detail, respectively, of aringed mesh-type flow reducing implant embodiment, in accordance with anexemplary embodiment of the invention;

FIG. 11 is an isometric view of a partially covered mesh-type flowreducing implant embodiment, in accordance with an exemplary embodimentof the invention.

FIG. 12 is an isometric view of a sheath-type flow reducing implant, inaccordance with an exemplary embodiment of the invention;

FIG. 13 is longitudinal section of an inflatable tube-type flow reducingimplant, in accordance with an exemplary embodiment of the invention;

FIG. 14 is a longitudinal section of a flow reducing implant withshape-conforming elements, in accordance with an exemplary embodiment ofthe invention; and

FIG. 15 is a plan layout of a cord-type flow reducing implant, inaccordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is a schematic showing of a flow reducing implant 100 installedin a coronary sinus vein 102, in accordance with an exemplary embodimentof the invention. Coronary sinus 102 drains a plurality of cardiac veins106 into a right atrium 104. The cardiac circulation is generallyhierarchical and comprises of stages of reducing (or increasing)diameter. Thus, veins 106, in turn, drain a plurality of thin venules108, which, after a few stages, drain a plurality of capillaries 110.Capillary 110 is fed by a plurality of arterioles 112, which, after afew stages, are fed by a plurality of coronary arteries 114 and 120. Astenosis 116 is shown in a coronary artery 114. While the cardiaccirculation is generally hierarchical, some connection exists betweendifferent branches. Occasionally, the existence of stenosis 116 willcause a collateral connection 118 to spontaneously form (or widen anexisting connection) between coronaries 114 and 120, bypassing stenosis116.

In some cases, however, this spontaneous formation does not occur. In anexemplary embodiment of the invention, a flow reducing implant 100 isplaced in coronary sinus 102 and has a narrowing significant enough toencourage the formation of collateral connection 118. It is hypothesizedthat collateral connection 118 is caused by an increase in venous bloodpressure, which, in turn, increases the pressure in the capillariesand/or causes retro-flow in the capillaries and/or causes drainage ofthe capillaries directly into the heart. However, even if thishypothesis is incorrect, several studies, that included numerousexperiments and actual procedures have shown that constriction ofcoronary sinus 102 will generally cause the formation of collateralcirculation and/or otherwise improve the condition of patients withblocked coronary arteries. Alternative or additional hypotheses that areoptionally used to select the constrictive effect of flow reducingimplant 100 include:

(a) Flow reducing implant 100 increases the pressure in the coronarycapillaries, thus increasing perfusion duration.

(b) An increase in resistance of the venous system causes redistributionof blood flow in coronary arteries.

(c) An increase in resistance of venous system increasesintra-myocardial perfusion pressure and/or intra-myocardial pressure.

(d) Increasing the arterial diastolic pressure (by restricting venousdrainage) causes the arterial auto-regulation to start working again,for example, such an auto regulation as described in Braunwald “HeartDisease: A Textbook of Cardiovascular Medicine”, 5th Edition, 1997, W.B.Saunders Company, Chapter 36, pages 1168-1169.

It should be noted that the selection of flow reducing implant 100 maybe made to achieve one or more of the above suggested effects,optionally to a desired degree and/or taking into account safety issues,such as allowing some drainage and maximum pressure allowed by thecoronary venous drainage system.

FIG. 2 is a schematic side view of flow reducing implant 100, inaccordance with an exemplary embodiment of the invention. Flow reducingimplant 100 comprises a narrowed section 204 and at least one flaredsection 200 (and 202) leading into narrowed section 204. Section 200(and 202) includes sections 210 and 206 that are inclined relative tothe wall of coronary sinus 102 and sections 212 and 208 that areparallel to the wall.

In the exemplary embodiment and measurements shown, flow reducingimplant 100 is expandable and shortens somewhat during expansion: havinga length of 20 mm before expansion and about 18.8 mm after expansion.Optionally, a non-shortening design is used, for example a mesh as inperistaltic stents, such as described in U.S. Pat. No. 5,662,713, thedisclosure of which is incorporated herein by reference. An exemplarymaterial thickness is 0.15 mm, however, thinner or thicker materials maybe used. Other exemplary lengths are 5 mm, 12 mm, 24 mm, 35 mm 45 mm andany smaller, intermediate or larger size. The length is optionallyselected to match a physiological size of the target vein (e.g., lengthand curves) and/or to ensure good contact with vein walls. The length ofnarrowed section 204 may be, for example, 0.5 mm, 1 mm, 2 min, 3 mm, 5mm or any smaller, intermediate or larger length, for example selectedto achieve desired flow dynamics An exemplary inner diameter of theflared sections is between 2 mm and 30 mm, for example, 5 mm, 10 mm, 15mm, 20 mm or any larger, smaller or intermediate diameter, for exampleselected to match the vein diameter. The inner diameter of the narrowedsection may be, for example, 1 mm, 2 mm, 3 mm, 5 mm, 10 mm or anysmaller, larger or intermediate diameter, for example selected toachieve desired flow dynamics and/or a pressure differential across theflow reducing implant.

In an exemplary embodiment of the invention, the ratio between thecross-section of narrowed section 204 and the flares of flow reducingimplant 100 is 0.9, 0.8, 0.6, 0.4, 0.2 or any larger, smaller orintermediate ratio, for example selected to achieve desired flowdynamics and/or a pressure differential across the flow reducingimplant.

While a circular cross-section is shown, other cross-sections may beused, for example, polygonal and ellipsoid. A potential advantage ofnon-circular cross-sections is that the implant is less likely tomigrate axially and/or rotate. Alternatively or additionally, theoutside of the flow reducing implant is roughened and/or otherwiseadapted to adhere to the vein wall. The cross-section shape and/ororientation optionally changes along the length of flow reducing implant100.

FIG. 3A is a plan layout of a slit-type flow reducing implant and FIG.3B is a detail of FIG. 3A, in accordance with an exemplary embodiment ofthe invention. In this plan layout, the ends of sections 200 and 202 arecaused to be parallel to the vessel wall when flow reducing implant 100is expanded.

In an exemplary embodiment of the invention, the outside flare of flowreducing implant 100 is defined by sections 340, 342 and 344, shown inFIG. 3B. Optionally, the total length of these sections defines themaximum flare length. Alternatively or additionally, the bending areasin and between these sections define the relative force required toexpand the flare region relative to the area near the rim. If the rimregion is more difficult to expand and/or is expanded less than theadjacent regions, the expansion of flow reducing implant 100 will tendto cause the rim to be bent in, or at least not flare out.Alternatively, in a self-expanding flow reducing implant, the existenceof sections 340, 342 and 344 can be used to determine the final shape ofthe flare. Optionally, additional sections 346 are provided around thecircumference of flow reducing implant 100, which define outer slits inflow reducing implant 100, which outer slits may have a maximumexpansion that is the same or smaller than that nearby (axially inwards)slits. This design can also be used to control the shape of the flare.

In an exemplary embodiment of the invention, a flow reducing implant ischaracterized by this maximum diameter, which may be used, for example,for selecting a particular flow reducing implant to match a patient.Optionally, during expansion, the balloon is aligned with flow reducingimplant 100 so that it only contacts the flare region or only contactsthe non-flare regions of flow reducing implant 100.

FIG. 3C is an isometric view of flow reducing implant 100 (FIG. 3A),mounted on a balloon catheter delivery system 302, in accordance with anexemplary embodiment of the invention.

In an exemplary embodiment of the invention, flow reducing implant 100is formed by cutting out of a sheet of metal or a tube, for example,using laser, water cutting, chemical erosion or metal stamping (e.g.,with the result being welded to form a tube). Alternatively, flowreducing implant 100 is woven (e.g. of metal or plastic fiber), forexample, using methods as well known in the art. Optionally, narrowedsection 204 is made using a different method from flared sections 200and 202, for example, the flared sections being woven and the narrowedsection being cut from sheet metal. In an alternative embodiment of theinvention, flow reducing implant 100 includes with a constraining ringthat prevents the expansion of narrowed section 204. Optionally, therestraining ring is plastically expandable, possibly under a higherpressure than the rest of flow reducing implant 100, which may beplastically deformable or self-expanding. Alternatively or additionally,the restraining ring is selected to set the desired degree of narrowing,and then mounted on a flow reducing implant, a stent or a stent graft,for implantation. In a sleeve flow reducing implant (FIG. 9G) a similareffect may be achieved by suturing the stent graft.

Upon attaining its destination, a standard balloon catheter with asingle expansion area, for example the Fox Catheter™ by Jomed, inc., maybe used to encourage the implant to attain its contoured shape. As theballoon presses against lumen of the implant, the narrowed section isprevented from expanding while flared sections 200 and 202 expand underpressure. Various methods for preventing the narrow section fromexpanding are described below, for example, providing differentmechanical properties, different designs or additional elements at thenarrowed sections relative to the non-narrowed sections.

In an alternative embodiment, flow reducing implant 100 is cut out of asheet and then spirally twisted around a mandrel to form the shape offlow reducing implant 100. Alternatively, flow reducing implant 100 iscut out of a tube, with the flared parts being spiral cuts and thenarrowing part being a ring cut. Alternatively, flow reducing implant100 is formed as a coil spring, with axially varying relaxationpositions.

In an exemplary embodiment of the invention, flow reducing implant 100is adapted for use in a coronary sinus or other coronary vein or otherveins having non-muscular walls. Veins are typified by having a lowdegree of elasticity and being relatively sensitive to tears (ascompared to arteries). In one example, the edges of flow reducingimplant 100 are curved inwards or curled, for example as shown byreference 130 in FIG. 1, Alternatively or additionally, the edges arefolded back and/or smoothed to remove sharp edges. Alternatively, theparallel sections 208 and 212 (FIG. 2) are made long enough to supportflow reducing implant 100 without harming coronary sinus 102.Alternatively or additionally, flow reducing implant 100 or at least alarger diameter portion thereof, is made soft enough and/or with a lowspring constant, to prevent flow reducing implant 100 from applying toomuch pressure on the coronary flow reducing implant wall. Alternativelyor additionally, the flares of flow reducing implant 100 are coated witha biologically inert flexible coating, for example, a soft siliconeelastomer or another soft plastic or rubber material such as Latex,Teflon and/or Polyurethane (for example Angioflex, a biologically inertpolyurethane plastic).

FIGS. 4A-4B are plan layouts of slit-type flow reducing implant 100, inaccordance with an exemplary embodiment of the invention. In FIG. 4B,rim 402 is defined by sections 440 and 446. As shown, these sections aredesigned to provide a relative smooth rim, possibly with small amountsof distortion (so rim 402 remains smooth) where the sections connect tosections 442 and 444. Together, sections 442, 444 and 446 define outerslits for rim 402.

Patients that are candidates for an angiogenesis-promoting procedure mayhave significant vascular compromise of the coronary circulation withconstriction and/or lack of flow in one or more coronary arteries thatsupply blood to the coronary tissue. An invasive surgical procedure,even to percutaneously introduce and/or position a reducing implant 100into the coronary sinus, may trigger a cardiovascular accident withuntoward sequella. Hence, averting and/or limiting the amount of timethat the vasculature is invaded, for example, during use of a ballooncatheter is desirable in some individuals.

FIGS. 4C-4D are a plan layout and isometric view, respectively of aslit-type flow reducing implant 1100 with a smooth rim, in accordancewith an exemplary embodiments of the invention.

In an exemplary embodiment of the present invention, slit-typeflow-reducing implant 1100 comprises shape memory materials thatautomatically achieve a final configuration state upon exiting, forexample, a delivery catheter or sheath, thereby averting the use of aballoon catheter for initial installation of slit-type flow-reducingimplant 1100. Alternatively, a balloon expended material, for exampleone that plastically deforms by expansion, may be used.

In an exemplary embodiment, slit-type coronary flow-reducing implant1100, shown in a plan view in FIG. 4C, contains preformed slits 1102, inaccordance with an exemplary embodiment of the invention. Slits 1102(and optionally a set of slits 1104 in a second or further row) define arow 1122 (and a row 1124) along an outer edge 1132 of slit-typeflow-reducing implant 1100 that, in the unexpanded state comprise atleast one edge 1132 that has a wavy configuration. Upon expansion, forexample shown in FIG. 4D, edge 1132 becomes smooth while slits 1102assume a rectangular appearance, with edge 1132 transverse to a slit1126, for example. In an exemplary embodiment of the invention, theslits of the rim are wider than the slits of the rest of implant 1100,thereby affecting its final expanded configuration.

In an exemplary embodiment of the present invention, slit-type coronaryflow-reducing implant 1100 is transferred to its deployment site incoronary sinus using a guide sheath without accompaniment by a ballooncatheter. As slit-type coronary flow-reducing implant 1100 reaches itsdestination and exits its guide sheath, coronary flow-reducing implant1100 automatically expands into its final shape, shown in FIG. 4D. Inthis manner, slit-type coronary flow-reducing implant 1100 does notrequire manipulation and/or expansion using, for example, a ballooncatheter.

Alternatively or additionally, a balloon catheter may be used tofacilitate expansion of slit-type flow-reducing implant 1100, forexample, when it is made of materials that do not automatically attain amemorized shape. In an exemplary embodiment, rows of slits 1122 and/or1124 have lengths and/or orientations that promote flow-reducing implant1100 to form into a final shape under pressure of a balloon catheter,therefore, installing with a minimal amount of time and/or stress to thesurrounding tissue.

In an exemplary embodiment, slit-type coronary flow-reducing implant1100 is designed to alter its shape in response to manipulation and/orexpansion following installation. In an exemplary embodiment, slits 1138expand so that a narrow passage 1168 automatically attains a firstdiameter during installation. In an exemplary embodiment, followinginstallation of slit-type coronary flow-reducing implant 1100, a ballooncatheter is introduced into narrow passage 1168 and inflated to pressradially outward on narrow passage 1168. In an exemplary embodiment, apressure, for example, of between 7 and 8 atmospheres or less than 7 orgreater than 8 atmospheres, depending, for example on the stiffness ofthe component materials, causes expansion slits 1138 to expand to alarger cross section. This causes narrow section 1168 to have a largerdiameter than it had immediately following installation.

While not shown, some of the slits, for example slits 1138 may beoblique, thus possibly requiring a different degree of force to expandand/or providing a twisting of the deployed implant. Providing opposingoblique slits may be used to providing a shortening of the implant.

In an exemplary embodiment, when flow-reducing implant 1100 isinstalled, little or no blood migrates through the walls of narrowpassage 1168 and/or a flare 1160 to contact the walls of the coronarysinus. This, for example, is achieved by a narrow configuration of theslits. Alternatively or additionally, the length of the slits decreasesnear narrowing 1168.

In an exemplary embodiment, to achieve limitation and/or cessation ofblood flow through the implant walls, the slits (e.g., not only slits1102 and 1104 at the rim) are increased in number, while their width isreduced. The viscosity of the blood impedes its flow through thedecreased width of the slits while the increased number of slits mayfosters expansion of implant 1100. This may result in a net reduction inblood flow through the implant walls.

Alternatively or additionally, the slit width may be used to help definethe device geometry. For example, slits (actually spaces) 1104 are widerthan the other slits. If, for example, slits 1104 are made wider thanslits 1102, a curved in rim may result.

Also shown is an optional design in which slits are arranged inalternating rows of long and short slits. Alternatively or additionallyand as shown, the size and/or density of slits is larger near the rimsthan near the center of implant 1100. Alternatively or additionally andas shown, the length of the slits increases as a function of thedistance from narrowing 1168.

As shown in FIG. 4D, the material of implant 1168 is distorted by theexpansion. Alternatively or additionally, the slits are distorted andthe material is distorted to conform to these distortions. For example,in one implantation, the short axial slit nearest the rim achieves atrapezoid rather than rectangular shape. In general, the expandedconfigurations are idealized, with an actual expanded shape possiblyincluding step-like distortions caused by the discrete pattern of theslits in the implant.

FIG. 5 shows a vascular path to coronary sinus 102, in accordance withan exemplary embodiment of the invention. Desirably, flow reducingimplant 100 is implanted using a trans-vascular approach, for example,from the venous system or by crossing through an intra-chamber wall inthe heart. In an exemplary embodiment of the invention, the deliverysystem is inserted through a jugular vein 510 or a subclavian vein 512to a right atrium 506 of a heart 500 via a superior vena cava 508 and/ora femoral vein 502, via an inferior vena cava 504. Once in right atrium506, the delivery system is guided (e.g., through a sharp bend) to anopening 514 into coronary sinus 102. In some patients, a valve exists atthe entrance to coronary sinus 102.

FIGS. 6A-6C are three exemplary vise embodiments, 1000, 1010 and 1020,that reduce flow through a blood vessel 1002, and are applied fromoutside the blood vessel, in accordance with exemplary embodiments ofthe invention. Vise 1000 (FIG. 6A) is a band having any ratchetmechanism for preventing opening as known in the art; vise 1010 is aclip-like clasp; and vise 1020 is an elastic spiral.

In an exemplary embodiment of the invention, the band, clip and/orspiral are distortable. In one example, if the narrowing is too great, aballoon catheter can be inserted into the vessel and expanded, causingthe spiral, clip and/or band to distort. In one example, the bandcomprises a plurality of slits (e.g., as in FIG. 8A), that accommodatesuch distortion.

FIGS. 6D-6F show three exemplary clamp embodiments, 1030, 1040 and 1050,that reduce blood flow through vessel 1002, in accordance with exemplaryembodiments of the invention. Clamp 1030 is a clip that shuts down partof the cross-section of vessel 1002; clamp 1040 is also a clip, thatonly distorts the cross-section of vessel 1002; and clamp 1050 is a tack(or suture) that transfixes a part of vessel 1002. Non-piercing clipsare optionally designed to have rounded tip and/or non-meeting tips toreduce danger of piercing.

FIG. 6G illustrates an exemplary endoscopic tool 1060 for releasingblood vessel reducing clip 1010, in accordance with an exemplaryembodiment of the invention. Clip 1010 is held between a flat plate 1060and a Trans-axially movable arm 1062 with a broadened tip. Retractingarm 1062 towards tool 1060 causes the clip to open and moving arm 1062in a Trans-axial direction frees the clip. Various other clip deploymentmechanisms (for plastic and elastic materials) are known in the art andmay be used. In an exemplary embodiment of the invention, the procedureis performed through a key hole and using a working channel or adifferent keyhole to provide visual verification of the procedure.Alternatively or additionally, radiological verification may beprovided. Various implants are known in the art for applying bands toblood vessel and may be used for the example of FIG. 6A as well.

Flow-reducing implants 1000, 1010, 1020, 1030, 1040 and/or 1050 may bedeployed on vessel 1002. Alternatively, these implants may be deployedonto tissue enclosing vessel 1002. For example, in the case of thecoronary sinus, the implant may be deployed onto (and/or piercingthrough) a pericardium and/or cardiac muscle tissue.

FIGS. 7A and 7B are a plan view and an isometric view of a flow reducingimplant 1200 with anchors, in accordance with an exemplary embodiment ofthe invention.

In an exemplary embodiment of the present invention, an anchor-typeflow-reducing implant 1200 comprises at least one anchor 1202 thatprevents motion of anchor-type flow-reducing implant 1200 in relation toa blood vessel. Optionally, at least one anchor 1202 and/or 1204 areparallel to the blood vessel and catch on the tissue of the blood vesselto prevent displacement of anchor-type implant 1200. While the anchorsare shown as flat, blunt and axial tabs, other designs may be used, forexample, sharp, curled and/or oblique to the vessel axis.

Alternatively or additionally, implant 1200 comprises one of row ofanchors 1202 and/or row of anchors 1204 that prevent motion. In anexemplary embodiment, anchors 1202 and/or 1204 are substantiallyparallel to the longitudinal axis of implant 1200 when it is in thenon-expanded state and in the expanded state, shown in FIG. 7B. In anexemplary embodiment of the invention, this parallel layout is achievedby the anchors being attached only to the rims and not the flaringsection of the implant. thus, they tend to stay in the plane of the rim,which may be, for example parallel to the blood vessel wall or evenpointing the anchors towards the wall (e.g., if the rim is curled in)

In an exemplary embodiment, anchor 1202 and/or 1204 are connected toanchor-type flow-reducing implant 1200 and protrude from its surface tointo the surrounding tissue with a pressure sufficient to prevent motionof the implant without causing tissue irritation. This can be importantin veins, for example, that have less thickness than comparablearteries.

In an environment where the vascular tissue is not uniform in diameterand/or tends to stretch, for example in the coronary sinus, or in othersituations, anchors that press with greater force or are pre-stressed toa greater non-parallel angle into the surrounding tissue may bedesirable. In an exemplary embodiment, anchor 1202 and/or 1204 aredesigned for such a vessel and press radially outward from the wall ofanchor-type flow-reducing implant 1200, against the surrounding tissue.

The design of anchor-type flow-reducing implant 1200 includes anchors1202 that have a free end that is not attached to narrow passage 1168and, for example, blunt to avert tissue irritation. In an exemplaryembodiment, one or more deployed anchors 1202 are parallel to alongitudinal axis 1210 of anchor-type flow-reducing implant 1200, andpoint towards one or more anchors 1204.

At a merging point of two vessels, the vessels may form a lumen with anellipsoid cross section. An anchor-type flow-reducing implant withanchors 1202 and/or 1204 that point toward one another may tend tomigrate laterally and/or displace to one side of the other of the lumen.In an exemplary embodiment, anchors 1202 and/or 1204 of anchor-typeflow-reducing implant 1200 may be configured to compensate fornot-cylindrical implantation environments.

For example, anchors 1202 and/or 1204 may be configured to point in asubstantially perpendicular direction to longitudinal axis 1210 ofanchor-type flow-reducing implant 1200, thus tending to prevent lateralmovement of implant 1200. In still another embodiment, anchors 1202and/or 1204 may be connected to an edge 1232 and pointing away fromanchors 1204 that are connected to an edge 1234. In this way, anchors1202 and/or 1204 press into tissue at the edge of the implant that isstronger and/or exhibits a more uniform circumference.

Alternatively or additionally, anchors 1202 and/or 1204 can be orientedin an oblique direction oblique to a transverse axis 1220 and/orlongitudinal axis 1210, for example, to prevent migration in anenvironment where there is strong flow force of the blood stream thattends to exert force and displace implant 1200.

While the anchors are shown cut out of the long slits, alternatively oradditionally, the anchors may be cut out of short slits, for example aslit 1125.

FIG. 8A is a portion of a plan layout of a section of a flow reducingimplant 800 with selective narrowing control, in accordance with anexemplary embodiment of the invention. Flow-reducing implant 800includes a narrowed section 804. However, section 804 is alsoexpandable, for example, having a plurality of thin slits 806 definedtherein. This allows the minimum diameter of flow-reducing implant 800to be increased after deployment.

In an exemplary embodiment of the invention, section 804 is stiffer thanthe rest of flow-reducing implant 800, so that pressure suitable forexpanding flow-reducing implant 800 will not expand section 804.Alternatively, flow-reducing implant 800 is a self-deploying implant andsection 804 is plastically deformed using a balloon. Thus, a deliverysystem used for flow-reducing implant 800 may include both a restrainingelement and a balloon element. In case the implantation of aflow-reducing implant fails, extreme expansion of section 804 willsubstantially negate the function of flow-reducing implant 800 and mayallow a new flow-reducing implant to be implanted within or throughflow-reducing implant 800, at a later time.

Alternatively, as shown, two sizes of slits 806 are provided, with thedegree of resistance to defamation being determined by the sizes and/orrelative sizes of the slits.

FIG. 8B is a side cross-sectional view of a flow reducing implant 820and a matching reducing catheter 840, which can be used to reduce thenarrowing of implant 820, in accordance with an exemplary embodiment ofthe invention. Flow-reducing implant 820 can be formed generally likeflow-reducing implant 800, in that its narrowed section has a selectablediameter. Flow-reducing implant 820 includes a plurality of engagementpoints 822 that are adapted to be engaged by a plurality of engagers 846of a catheter 840. Various designs of engagers and engagement points maybe used. In the example shown, engagement points 822 include aprotruding arc 824 that is engaged by a barbed tip at engager 846. In anexemplary embodiment of the invention, catheter 840 includes a bodyhaving a diameter similar to (or smaller, e.g., to allow forspring-back) the desired final diameter of flow-reducing implant 840.When engagers 846 are inserted adjacent to engagement points 822 andcatheter 840 is rotated, the barbs engage the arcs. One or more wires844 are retracted, retracting engagers 846 and arcs 824 towards catheterbody 842. In an exemplary embodiment of the invention, body 842 distortsbarbs 846 so that they release arcs 824 so that catheter 840 can beremoved. Alternatively, other engagement/release mechanisms can be used,for example, barbs that match apertures in flow-reducing implant 820 orprovision of grasping heads (e.g., pliers) at engagers 846. Optionally,the narrowing procedure is performed under medical imaging, for example,fluoroscopy.

In an alternative embodiment of the invention, engagement means such asbarbs 846 are used to remove the entire flow-reducing implant,optionally for replacement with a different flow-reducing implant and/orre-deployment of the same flow-reducing implant using a balloon oncatheter 840 or after removal from the body.

Alternatively or additionally, the flow-reducing implant is removed inthe following manner. Flow-reducing implant 820 is a shape memoryflow-reducing implant that expands when subjected to body temperature. Aballoon having cool fluid circulating there through is brought intoflow-reducing implant 820 to cause flow-reducing implant 820 to shrinkback to an unexpanded configuration and/or be more amenable for removal.

In some cases however, the decision to remove and/or change a diametermay be made only after a time period, during which vascular tissue mayhave grown into and attached onto flow-reducing implant 820.

FIG. 8C is a two-part flow reducing implant 850 including a tubularsection 852 and a reducing section 854, in accordance with an exemplaryembodiment of the invention, Reducing section 854 may be manufactured tomatch tubular section 852 or it may be a flow-reducing implant design asdescribed herein or a flare, for example. In either case, tubularsection 852 is optionally used to isolate reducing section 854 from theenclosing vascular tissue, thus allowing easier manipulation and/orreplacement of section 854. Alternatively or additionally, for examplein the coronary sinus, the use of tubular section 852 may be desirablefor prevention of damage to the vascular tissue. Alternatively oradditionally, tubular section 852 is provided for other reasons, forexample, to provide support for axial fixation of reducing section 854and/or to reduce damage to a surrounding blood vessel. Depending on theembodiment, tubular section 852 and reducing section 854 may be ofsimilar sizes or tubular section 852 may be considerably longer, forexample, 25%, 50%, 100%, 200%, 400% or any smaller, intermediate orgreater size ratio. The two sections may be inserted at the same time orat different procedures. The two sections may be inserted using a samedelivery system or, for example, using two separate delivery systems.Tubular section 852 may be of various designs, for example, be a coil ormesh stent, a stent graft, a graft with stents (or other attachmentmeans) at its ends and/or a plain graft. Tubular section 852 and/or thetips of a flow-reducing implant may be made flexible and/or elastic toadapt to changes in blood vessel diameter.

FIG. 8D is a flow reducing implant 860 including a narrowing insert toreduce the diameter of implant 860, in accordance with an exemplaryembodiment of the invention. Insert 870 has its expansion insideflow-reducing implant 860 limited by a narrowed diameter section 862 offlow-reducing implant 860. In an exemplary embodiment of the invention,insert 870 has a funnel shape, with a narrow diameter opening 874 and alarger diameter opening 876. Insert 870 may be formed, for example, froma mesh and may be plastically, elastically, super-elastically and/orshape-memory deformed. In an exemplary embodiment of the invention, thefinal geometry of insert 870 is defined by its resting points againstflow-reducing implant 860. This resting points comprise, for example, apoint 864 generally between the narrow and flared sections offlow-reducing implant 860 and a resting point 866 on the flared sectionof flow-reducing implant 860. In an exemplary embodiment of theinvention, a ratchet mechanism is provided to anchor insert 870 inplace. Optionally, opening 874 is narrowed further (if required), byadvancing opening 876 towards narrowed section 862 of flow-reducingimplant 860. Alternatively or additionally, overcoming the ratchetmechanism and retracting opening 876 from section 862 enlarges opening874. In an exemplary embodiment of the invention, the ratchet mechanismcomprises a plurality of inclined barbs or anchors 868, on flow-reducingimplant 860. Alternatively or additionally, the ratchet mechanism and/orlocking mechanism comprises a barb 872 on insert 870. These ratchets maybe overcome, for example, by reducing the size of opening 876 and/or byapplying considerable force against the ratchet direction.

Alternatively or additionally to the above described methods ofnarrowing an implanted flow-reducing implant, in an exemplary embodimentof the invention, a band or clip is applied to the outside of theenclosing blood vessel, urging flow-reducing implant 820 (e.g., at itsnarrow and/or broad sections) to close. Alternatively, the band isapplied alone, without a flow-reducing implant. Exemplary bands andother implants are described in FIG. 6A-6G. Such implants may be used toplastically urge flow-reducing implant 820 closed, in which case, apliers (optionally adapted to pass through a keyhole) may be usedinstead of a permanent clamp. The jaws of the pliers are optionallyformed to have a cross-section matching desired cross-section offlow-reducing implant 820.

Alternatively, flow-reducing implant 820 is elastic or super-elastic,and a permanent implant is implanted outside the blood vessel. In anexemplary embodiment of the invention, the band or pliers is appliedover a wide area, for example, 30%, 50%, 80% or any greater intermediateor smaller percentage of the length of flow-reducing implant 820, toreduce damage to the blood vessel. Alternatively or additionally, thenarrowing effect is applied to a weakened part of flow-reducing implant820, for example, a broad section thereof.

In some locations, for example in larger arteries exhibiting large flowvolume and/or blood pressure, flow of blood through slits 1125 (FIG. 7B)may add to turbulence of blood flowing through flow-reducing implant1100. Such turbulence may contribute to the formation of blood clotsthat cause embolitic sequella, for example a stroke, at distantlocations in the body. While using a single implant with walls that donot have slits may alleviate this problem, flow-reducing implants withnon slit walls may not exhibit appropriate expansion capabilities and/orfacilitate in situ revision of its configuration.

FIG. 8E is an isometric view of a dual layer flow-reducing implant 1400in accordance with an exemplary embodiment of the invention. In anexemplary embodiment, dual layer flow-reducing implant 1400 comprises afirst flared section 1450 and/or a second flared section 1460. Forpurposes of clarity, the components of flare 1460, alone, will befocused on, though similar features can be applied to flared section1450.

In an exemplary embodiment, dual layer flow-reducing implant 1400comprises a flared section 1460 comprising an external cone 1420 and aninternal cone 1410. Internal cone 1420, for example, comprises slits1422 and 1426 and external cone 1410 comprises slits 1412 and 1416 sothat cones 1410 and 1420 can be transported to an implantation site in anon-expanded state and expanded at the implantation site.

Further expansion of cone 1410 and/or 1420 may be desirable and can beincorporated into their respective designs so that cone 1410 and/or 1420expand to a first diameter when pressed radially outward by a ballooncatheter at a first expansion pressure. Cone 1410 and/or 1420 can thenexpand to a second, greater, diameter when pressed radially outward by aballoon catheter at a second, greater, expansion pressure.

In an exemplary embodiment, when slits 1422 and 1426 are aligned withslits 1412 and 1416 respectively, blood flows in a direction 1451 (e.g.,in a space 132 shown in FIG. 1) and through slits 1432 and 1436. Withalignment of slits 1412 with 1422 and/or slits 1416 with 1426,flow-reducing implant 1400 may be implanted into a vessel with arelatively slow flow speed and/or low pressure. For example, withimplantation in the coronary sinus narrow area 1440 may fill with tissuethat aids in anchoring implant 1400 without risk of an embolism.

Alternatively or additionally, as there is limited or cessation of flowinto space 132, a clot forms in area 1440 and stabilizes in itsposition. Stabilized clot in area 1440 becomes incorporated into thesurrounding tissue and against dual cone flow-reducing implant 1400 sothat it is further stabilized in its position.

In an exemplary embodiment, slits 1422 and 1426 can be rotated, prior toimplantation, in relation to slits 1412 and 1416 so that blood flow indirection 1451 is substantially stopped to various degrees. Withmisalignment of slits 1422 and 1426, reducing implant 1400 may beimplanted into a vessel with a relatively higher flow speed and/orhigher pressure, for example a main trunk of an artery therebyprotecting the patient against the dangers of embolism migration.

The alignment of slits 1422 and 1426 is optionally set prior toimplantation in a blood vessel in relation to slits 1412 and 1416, inorder to establish a pre-defined blood flow pattern, and the two layersexpanded or allowed to expand, together. To ensure that cones 1410 and1420 remain fixed in position in relation to each other, cones 1410and/or 1420 have, for example, a friction surface interface and/orinterdigitation. Alternatively or additionally, the two layers may bedeployed in different ways, for example, the inner layer may beplastically deployed and the outer layer self-deployed. Possibly, theprofile of the two layers does not match along its entire length.Alternatively or additionally, the outer layer is plastically deformedby a self-deploying inner layer (which self deployment may also providethe friction for locking). Alternatively or additionally, cone 1420 maybe rotated, for example using a suitable internal engaging catheter,after implantation

The flared sections 1450 and 1460 need not be symmetric. For example,the implant may also selecting between flow blockage at one section, theother and optionally both. Flow only into space 132, may assist in clotformation. Flow only out of space 132 may assist in collapsing asurrounding blood vessel,

FIGS. 9A-9G illustrate various flow-reducing implant variations, inaccordance with exemplary embodiments of the invention. While asigmoid-like flare is shown, a linear or other flared design may also beprovided.

FIG. 9A is a flow-reducing implant 900 with having a narrowed section902 and a single flared section 904. Narrowed section 902 may pointupstream or down stream. One potential advantage of this design is thatthe delivery system is less likely to get caught inside narrowed section902. Another potential advantage is that a completely obstructingimplant can be provided. In an exemplary embodiment of the invention,however, even such a completely obstructing implant has smooth sides, toprevent damage to the coronary sinus. Possibly, the outer diameter ofthe completely obstructing implant or a nearly complete flow-reducingimplant is increased beyond that of the coronary sinus, to preventdislodgment of the implant. Alternatively or additionally, one or morebarbs on the outside of the implant may be provided. Optionally, a coneshaped flow-reducing implant is provided with one or more openings forblood flow on the face of the cone, rather than at its apex as shown.

Alternately to a plain flow-reducing implant, the narrowing may be avalve, for example, a valve that opens, to a full or partial diameter,after a suitable pressure is achieved in the coronary sinus distal fromthe right atrium. For example, a leaflet valve or other type of vascularvalve as known in the heart may be provided.

FIG. 9B shows an alternative flow-reducing implant 910; with twonarrowed sections 912 and 916 sandwiching a flared section 914 betweenthem, in accordance with an exemplary embodiment of the invention.Optionally, the different narrowed sections have a different innerdiameter. Optionally, the narrowed sections are selectively expandedusing a balloon to achieve a desired pressure profile.

FIG. 9C is an alternative flow-reducing implant 920 with three narrowedsections 922, 926 and 929 and two flared sections 924 and 928 betweenthe narrowed sections, in accordance with an exemplary embodiment of theinvention.

Certain blood vessels may exhibit a taper along their length, forexample forming an angle 1310, shown in FIG. 9D. Vessels that change insize along their length may occur, for example, in the coronary sinus asit joins into the right atrium. In a tapered blood vessel it may bedesirable to utilize a tapered-type flow-reducing implant 930 (FIG. 9E),seen in detail in FIG. 9D, in accordance with exemplary embodiments ofthe invention.

FIG. 9D is an isometric view of an exemplary embodiment of a taperedflow-reducing implant 1300, (with a similar configuration to implant930) in accordance with an exemplary embodiment of the invention.Tapered flow-reducing implant comprises a smaller flared section 1330, anarrowed section 1340 and larger flared section 1320. The size ofsmaller flared section 1330, for example, is governed one or more slits1342 that are transverse to the axis of narrowed section 1340 and one ormore slits 1346 that are longitudinal to the axis of narrowed section1340.

The size of larger section 1320 is governed, for example, by two or moreslits 1322 that are transverse to the axis of narrowed section 1340and/or two or more slits 1320 that are longitudinal to the axis ofnarrowed section 1340.

Optionally, slits 1342, 1346, 1322 and/or 1326, be varied size and/orconfiguration to govern the shape of flared sections 1320 and/or 1330.Alternatively or additionally, slits 1342, 1346, 1322 and/or 1326 may behave various arrangements to provide different contours to flaredsections 1320 and/or 1330 and/or narrowed section 1340.

While openings 1330 and 1320 are shown as being round, they may have avariety of configurations to conform to different vessel configurationsas noted above. Further, the ratio between opening 1330 and 1320 may bevaried to conform to any vessel diameter where flow-reducing implant1300 is implanted. As in other figures, the material of the implant isshown distorted, while in some embodiments, it may be the slits,possibly in addition to the material, which is distorted.

FIG. 9E is a tapered flow-reducing implant 930 in which one flaredsection 932 has a smaller diameter than a second flared section 936, butlarger than an intermediate narrowed section 934, in accordance with anexemplary embodiment of the invention.

In FIG. 9F is a flow-reducing implant 940 that is not axially and/orrotationally symmetric around its axis, in accordance with an exemplaryembodiment of the invention. In an exemplary embodiment, a first flaredsection 946 is distorted relative to an axis defined by a second flaredsection 942 and a narrowed section 944.

Optionally, flow-reducing implant 940 is curved. In an exemplaryembodiment of the invention, asymmetric or curved flow-reducing implantsinclude special markings, for example, radio-opaque or radio-transparentareas, to assist correct orientation of flow-reducing implant 940 in ablood vessel.

FIG. 9G is a flow-reducing implant 950, in which a narrowed section 954is a sleeve 954, in accordance with an exemplary embodiment of theinvention. Sleeve 954, for example, is formed of a flexible graftmaterial, such as Dacron or GoreTex. Flow-reducing implant 950 furthercomprises at least one of two outer rings 952 and 956 that serve toanchor flow-reducing implant 950 in the blood vessel. A potentialadvantage of using a sleeve is that it can bend to conform to the veingeometry and/or dynamics. Other flow-reducing implant designs can alsobend. Optionally, the graft material is elastic, so it can serve as apressure limiting valve, to better control coronary sinus pressure.Optionally, a constraining ring is provided on the outside of section954, to restrict the lumen of flow-reducing implant 950. Optionally, thering is placed on flow-reducing implant 950 during the procedure, toachieve a desired narrowing effect. Alternatively or additionally, thering is expandable, for example using a balloon, to allow controllingthe narrowed section of flow-reducing implant 950. Optionally, the ringis sutured to narrowed section 954. Optionally, section 954 isstiffened, for example, using a wire, as known in the art ofstent-grafts.

In an exemplary embodiment of the invention, flow-reducing implant 100is provided in kit form, possibly with a delivery system, aflow-reducing implant diameter control system, additional flow-reducingimplants, external bands and/or other means for reducing its innerdiameter, and including instructions for use and/or size markings.Optionally, flow-reducing implant 940 is provided inserted into adelivery system or packaged with a delivery system.

As noted above, in some embodiments of the invention a flow reducingimplant is constrained by providing a band on the outside of theimplant.

FIGS. 10A-10B are an isometric view and detail, respectively, of aringed mesh-type flow reducing implant embodiment, in accordance with anexemplary embodiment of the invention. In an exemplary embodiment,mesh-type flow-reducing implant 1500 (FIG. 10A) comprises a flareshoulder 1502 and/or a flare shoulder 1504 that are relatively long inlength, for example, to increase the area of contact betweenflow-reducing implant 1500 and surrounding vessel walls. Alternativelyor additionally, tissue may grow through the mesh of flare shoulders1502 and/or 1504, providing good anchorage of mesh-type flow-reducingimplant 1500. Optionally, mesh-type flow-reducing implant 1500 comprisesand/or is coated with materials that promote tissue ingrowth. A rim1620, which may be, for example jagged or smooth is also optionallyprovided on each shoulder.

Optionally, the initial shape of mesh-type flow-reducing implant 1500 isgoverned by one or more bands 1522 and/or 1524 that constrict an area1528 of mesh-type flow-reducing implant 1500. In an exemplaryembodiment, the surrounding tissue collapses onto mesh-typeflow-reducing implant 1500 to reduce blood flow through the walls ofconstriction area 1528. While two bands 1522 and 1524 are shown, asingle band, for example band 1522 alone, may be used to createconstriction area 1528.

In an exemplary embodiment, an operator manually tying their endstogether, prior to implantation, adjusts the rings formed by band 1522and/or 1524 in circumference, for example. Adjustment of band 1522and/or 1524 prior to implantation allows the operator to establishconstriction area 1528 with a specific size to reduce blood flow andthereby promote angiogenesis. Alternatively or additionally, a ballooncatheter, for example, is expanded in area 1562 to cause expansion ofbands 1522 and/or 1524, thereby expanding area 1562 to increase bloodflow there through. In this fashion, blood reduction throughflow-reducing implant 1500 can be regulated prior to placement and/orfollowing placement of flow-reducing implant 1500 in a blood vessel.

In an exemplary embodiment, band 1524 rips when a large expansion forceis placed against it. To adjust the diameter of area 1528 followingimplantation, a balloon catheter is positioned inside area 1562 andexpanded until the pressure exceeds that which is required to rip band1524. With band 1524 ripped, the area of mesh area 1562 directly underit expands so that area 1562 expands in diameter so that it has thediameter of ring 1522.

Optionally, band 1524 has a smaller diameter than band 1522, providingtwo levels of expansion. For example, so that as a balloon catheter isexpanded to a first diameter, it expands smaller diameter band 1524,increasing the diameter of constriction area 1528 to a first expandeddiameter. Should further increase in flow be desired, a balloon catheteris expanded to a second diameter and expands larger diameter band 1524and/or smaller diameter band 1524, increasing the diameter ofconstriction area 1528 to a second expanded diameter.

Ring 1524 has, for example, a diameter of 6 millimeters while ring 1522has a diameter of 8 millimeters so that area 1562 has flow passage of 6millimeters. By expanding an expansion balloon inside area 1562 andcausing ring 1524 to rip, the area under ring 1524 expands. However,ring 1522, with its diameter of 8 millimeters, maintains its integrity.Hence area 1562 now has a flow passage of 8 millimeters (less thethickness of the mesh or other material from which the implant isformed.

FIG. 10B is a detail of an embodiment of ring 1522 comprising anadjustable band 1540 that forms ring 1522 and is held at a specificdiameter by a clasp 1544. Alternatively or additionally, adjustable band1540 is maintained at a specific diameter by a clasp 1546. In anexemplary embodiment, clasps 1544 and/or 1546 hold adjustable band 1540so that during implantation, ring 1522 remains at a specific diameteruntil, for example, an expanding balloon catheter is expanded againstadjustable band 1540 and the diameter of ring 1522 is expanded. In anexemplary embodiment, clips 1544 and 1546 comprise, for example, a nylonmaterial that holds band 1522 at a specific diameter and allow expansionof the diameter only under expansion pressure from, for example, aballoon catheter. Optionally, two clasps are provided, so no part ofband 1540 sticks out from the ring. In an exemplary embodiment of theinvention, the clasps are “C” shaped and band 1540 optionally includebumps that prevent sliding of the band through the clasps. Alternativelyor additionally, friction prevents such sliding.

In an exemplary embodiment, flare shoulders 1504 and/or 1502 are 0.5centimeters to 1 centimeter in length through they could be less than0.5 centimeters or greater than 1 centimeter in length, for example,depending upon vessel configuration.

In an exemplary embodiment, mesh-type flow-reducing implant 1500comprises strands that form its mesh comprising gortex, Dacron and/orsteel. Further, the material comprising the mesh can be configured to beflexible or rigid, depending, for example, on the materials, itsthickness, based upon, for example the flow dynamic dynamics desired.

FIG. 11 is an isometric view of a partially covered mesh-type flowreducing implant embodiment 1600, in accordance with an exemplaryembodiment of the invention. Mesh-type flow reducing implant 1600comprises a covering 1614 over or inside narrow section 1624, implantedin a blood vessel 1680, shown in cross section. In an exemplaryembodiment, mesh-type flow reducing implant 1600 comprises one or moreflare shoulders 1602 that contact blood vessel 1680 to provideanchoring. A rim 1620, which may be, for example jagged or smooth isalso optionally provided on each shoulder.

Alternatively or additionally, mesh-type flow reducing implant 1600comprises a covering 1614 the restricts blood flow through the surfaceof flow reducing implant 1600 and/or blood turbulence in an area ofconstriction 1624, thereby reducing danger of embolitic migrationproblems.

In an exemplary embodiment of the invention, covering 1614 comprises aseparate, flexible layer, that is attached to flow reducing implant 1600at several points (e.g., at constriction area 1624 and/or flareshoulders 1602) to prevent tearing when implant 1600 expands. Prior toexpansion, for example, covering 1614 is folded and/or pleated.Alternatively or additionally, covering 1614 has a low bulk and, forexample, is integrated into flow reducing implant 1600 structure, forexample, so that it substantially spans the open areas of the mesh.Examples of materials comprising covering 1614, include gortex, latexand/or silicone, on the inside and/or outside of flow reducing implant1600.

FIG. 12 is an isometric view of a sheath-type flow reducing implant2340, in accordance with an exemplary embodiment of the invention.Sheath-type flow reducing implant 2340 comprises a sheath 2342 thatencircles at least a portion of outer wall 102. Sheath-type flowreducing implant 2340 with a single sheath 2342 differs from implant 950(shown FIG. 9G) in which a narrowed section 954 is shown with two flaredsides and supported by stents or rings 952 and/or 956. Connected tosheath 2342 and/or an extension thereof is a sheath projection 2352,with an opening 2354 to allow passage of blood flow via lumen 2216.Sheath projection 2352, for example, can be configured with groovesand/or projections to further control the amount of obstruction of thecentral blood flow stream. In an exemplary embodiment of the invention,sheath 2352 includes a stiffener ring which maintains its openingpatent. Alternatively or additionally, one or more stiffening axial orradial struts are provided to assist in maintaining the shape of sheath2352.

FIG. 13 is longitudinal section of an inflatable tube-type flow reducingimplant 2400, in accordance with an exemplary embodiment of theinvention. Inflatable tube-type flow reducing implant 2400 comprises along wall 2406, a portion of which is surrounded by a ring-shaped tube2420. Optionally, tube 2420 can be located along any portion of longwall 2406 and/or of any configuration that reduces blood flow throughlumen 2114. In an exemplary embodiment of the invention, tube 2420replaces the function of ring 1522 of FIG. 10A.

In an exemplary embodiment, tube 2420 has an interior space 2430enclosed within a circular wall 2402 that is, for example, inflatableusing a hose 2428. In an exemplary embodiment, tube 2420 inflates sothat interior 2430 has two or more cross sectional diameters, therebyallowing adjustment of narrow lumen 2114 to modify the amount ofreduction in blood flow. Hose 2428 is optionally removed or torn offafter deployment. Alternatively or additionally, hose 2428 may beattached after deployment, for example having a needle tip used toinject fluid into tube 2420. Alternatively or additionally, tube 2420may be torn or punctured after implantation, to increase the diameter ofthe narrowing.

Alternatively or additionally, tube interior 2430 contains a materialthat absorbs liquid, thereby expanding. Following implantation, forexample, tube 2420 absorbs liquid and interior 2430 increases in sizeuntil tube 2420 reaches its expanded state.

Alternatively or additionally, wall 2402 and/or tube 2430 comprise aresilient material, for example Nitinol, and expand to a final statewithout inflation. Alternatively or additionally, flow-reducing implant2400, and/or embodiments mentioned below, are manufactured from abiocompatible material, comprising, for example, a soft siliconeelastomer and/or another soft material such as latex, Teflon, gortex,Kevlar and/or polyurethane.

Alternatively or additionally, interior 2430 is filled, for example witha spongy material, for example that is different from the materialcomprising long wall 2406 and/or wall 2402. Spongy material of interior2430, for example, remains compressed in a compact size until its exitfrom catheter 2122 whereupon interior 2430 expands, causing theexpansion of tube 2420.

In an exemplary embodiment, long wall 2406 is contoured and comprises ashape memory material and achieves its final state, including a bulge2404, upon exit from catheter 2122. Alternatively or additionally, longwall 2406 is, for example, not contoured and tube 2420 presses againstlong wall 2406 to create bulge 2404.

In an alternative embodiment of the invention, wall itself 2406comprises a balloon, which is inflated. Alternatively or additionally,wall 2406 is manufactured with a varying thickness, for example beingmade of a flexible plastic cylinder with its top and bottom reamed out.

FIG. 14 is a longitudinal section of a flow reducing implant withshape-conforming elements 2700, in accordance with an exemplaryembodiment of the invention. Shape-conforming element implant 2700comprises one or more shape-conforming elements 2720 and/or 2722 thatcan be remotely induced to change their configuration. Remote control ofthe configuration of elements 2720 and/or 2722 causes, for example,change in configuration, constriction and/or expansion of narrow lumen2742, flare 2744 and/or flare 2746 without associated hazards of aninvasive procedure. As narrow lumen 2742, flare 2744 and/or flare 2746change their configuration; the blood flow is obstructed to a greater orlesser extent, thereby promoting angiogenesis.

Shape-conforming elements 2720 and/or 2722, for example, are charged sothat as they receive impulses from impulses 2730 and/or 2732, theychange into one or more different geometric shapes and/orconfigurations. The shapes of elements 2720 and/or 2722 induced byimpulsers 2730 and 2732 changes the reduction in blood flow, therebyinfluencing angiogenesis.

For example, one or both shape-conforming elements 2720 and/or 2722straighten, they exert outward expansion pressure on narrow lumen 2742,thereby allowing blood flow there through to increase. When one or bothshape-conforming elements 2720 and/or 2722 bend further than depicted inFIG. 14 they pull the walls of narrow lumen 2742 inward, causing lumen2742 to narrow, thereby reducing blood flow there through.

Alternatively or additionally, when shape-conforming elements 2720and/or 2722 bend or straighten wall 2102 along narrow lumen 2742 maychange the obstruction of the lumen by wall 2102 to influenceangiogenesis.

Alternatively or additionally, shape-conforming elements 2720 and/or2722 are located exterior to flow-reducing implant 2700, for examplealong outer wall 2102. Alternatively or additionally, othershape-conforming elements 2720 and/or 2722 may be located along flares2744 and/or 2746 to provide additional and/or alternative remote controlof flow-reducing implant 2700.

Optionally, impulses provided by impulsers 2730 and 2732 to inducechanges in shape-conforming elements 2720 and/or 2722 and comprise oneor more of: RF, acoustic waves such as ultrasound and/or low frequencysound, heat, electricity, electromagnetic, radiation. Alternatively oradditionally, impulsers 2730 and 2732 mediate a chemical reaction thatmodifies elements 2720 and/or 2722, thereby changing theirconfiguration.

In an exemplary embodiment, a director 2738, external to the patient,directs impulsers 2730 and 2732 to provide impulses to shape-conformingelements 2720 and/or 2722, thereby causing the changes in geometricshape. Director 2738, for example, directs impulsers 2730 and 2732 viaradio waves from an antenna 2758. Impulses 2730 may be, for exampleratchet mechanisms or motors powered or stimulated by such signals, toshorten bands that surround the implant. In an exemplary embodiment ofthe invention, impulsers 2730 comprise one or more magnetic motors thatinclude a magnetic gear which is turned by the effect of a rotatingmagnetic field applied outside the body and which taming causes atightening of a band (e.g., 2722, 2720).

Alternatively or additionally, elements 2720 and/or 2722 are sensitiveto waves that are propagated external to the patient. For example,director 2738 provides one or more of: RF, acoustic waves such asultrasound and/or low frequency sound, heat, electricity,electromagnetic and radiation to influence the configuration of elements2720 and/or 2722. Impulsers 2730 and 2732 may then be optional, or beused only to provide a ratchet mechanism.

In an exemplary embodiment, shape-conforming elements 2720 and/or 2722comprise a material with a positive charge, for example positivelycharged plastic and/or silicone rubber. Alternatively or additionally,shape-conforming elements 2720 and/or 2722 comprise a negatively chargedmaterial.

Optionally, shape-conforming elements 2720 and/or 2722 are manufacturedfrom a material comprising charged lithium ions. In an exemplaryembodiment, waves cause the charged lithium ions to align, therebychanging the geometry of shape-conforming elements 2720 and/or 2722 tocause changes in the shape of outer wall 2102 and/or inner wall 2104.

In an exemplary embodiment, the strength and/or length of impulses aidin changing shape-conforming elements 2720 and/or 2722. For example,impulsers 2730 and 2732 provide an electric impulse of between 0.1 voltsand 0.5 volts (optionally, 0.1 volts or less or 0.5 volts or more), fora period of 10 msec or longer or 6 msec. or shorter. The factorsinfluencing the impulse chosen, for example, depend upon materialscomprising shape-conforming elements 2720 and/or 2722, theirresponsiveness to the impulses and/or the desired changes in theirshapes to influence the shape of flow-reducing implant 2700.

Flow-reducing implant 2700, with shape-conforming elements 2720 and/or2722 allows modification in shape and/or blood flow reduction followingimplantation of flow-reducing implant 2700 in coronary sinus 2110without an invasive procedure. Alternatively or additionally, anembodiment of shape-conforming element implant 2700 that assumes itsinstalled shape without, for example, the use of balloon catheter 1000may be desirable.

In an alternative embodiment, externally applied RF radiation isreceived by threads 2722 and 2720, which act as antenna and heat up,thereby expanding. Alternatively or additionally, such heating is usedto inflate a balloon band, for example by causing an irreversiblechemical reaction that releases gas.

FIG. 15 is a plan layout of a cord-type flow reducing implant 2900, inaccordance with an exemplary embodiment of the invention. In anexemplary embodiment, cord-type flow-reducing implant 2900, comprises apreformed shape that will easily spring into its installed shapewithout, for example, use of balloon catheter. Alternatively, a balloonbased expansion mechanism is provided. In an exemplary embodiment, oneor more edges 2910 are joined to one or more edges 2908 to formcord-type flow-reducing implant into a tubular shape with lumen 806passing there through.

In its assembled state, cord-type flow-reducing implant 2900 comprises arow of slits 2924 through which a cord 2954 passes, that is modifiedwith minimal expansion pressure from balloon catheter.

In an exemplary embodiment, cord 2954 is woven to pass under a lead post2982 and over a trailing post 2986 so that cord 2954 is woven acrosscord-type flow-reducing implant 2900. Alternatively or additionally,cord 2954 is expandable and attached to surfaces of slots 2924, forexample their surfaces facing lumen 2806 or their opposite (outside)surfaces. Optionally, the cord blocks blood flow through the wall of thereducer.

In an exemplary embodiment, after cord-type flow-reducing implant 2900expands to its initial configuration automatically upon exiting adelivery sheath. When further size modification is required, a ballooncatheter is introduced into the interior of cord-type flow-reducingimplant 2900. The balloon catheter is inflated, for example, between 3-4atmospheres (optionally, 3 atmospheres or less or 4 atmospheres ormore), to cause cord 2954 to expand (or it may be loose) radiallyoutward, thereby allowing slit 2958 to expand further and the diameterof the adjacent flared section to increase.

Alternatively or additionally, at least a portion of an edge 2910 isdetached from at least a portion of an edge and at least a portion edge2910 and edge 2908 overlap. When expansion is required, expansion forceis applied, for example, between 7-8 atmospheres (optionally, 7atmospheres or less or 8 atmospheres or more) is applied. Cord 2954, inresponse to the pressure, elongates (or is loose and tightens) so thatedge 2910 draws closer and/or passes edge 2908, allowing cord-typeflow-reducing implant 2900 to attain another, expanded, diameter.

In an exemplary embodiment, cord 2954 comprises a plastic material thatstretches to two or more lengths, depending upon the expansion pressurethat is applied to it. Hence, at a lower pressure, cord 2954 expands toa first length, thereby defining a first narrow diameter of cord-typeflow-reducing implant 2900. Subsequently a second expansion pressure isapplied and cord 2954 attains a second, longer, length, thereby defininga second diameter, wider than the narrow diameter.

Alternatively or additionally, cord-type flow-reducing implant 2900includes one or more diameters in which edge 2910 and edge 2908 areseparated by a space, thereby providing an interrupted lumen surface.Alternatively or additionally, cord 2954 severs upon application of, forexample, pressure between 9-10 atmospheres (optionally 9 atmospheres orless or 10 atmospheres or more). Upon severing cord 2954, edge 2910, forexample, maximally separates from edge 2908; thereby applyingunrestricted pressure against coronary sinus 2110.

In an exemplary embodiment, cord 2954 of flow-reducing implant 2900comprises a biocompatible material that dissolves in the environment ofcoronary sinus 2110, for example, a material comprising galactic acidand/or polygalactic acid and/or other materials with similar properties.In an exemplary embodiment, flow-reducing implant 2900 is placed incoronary sinus 2110 and the balloon catheter is used to expand it sothat its outer surface contacts the inside surface of coronary sinus2110. Over a period of time, for example cord 2954 degrades, dependingupon the biodissolvable material comprising cord 2954. (Optionally,degradation of cord 2954 occurs in less than three days or more thanthree days, dependent upon its composition and/or desired duty cycle.)Once cord 2954 has dissolved, flow-reducing implant 2900 retains and/orassumes a shape with its outer surface in contact with the inner surfaceof coronary sinus 2110.

With cord 2954 dissolved, further expansion of inner diameter offlow-reducing implant 2900 is accomplished with balloon 1010 at a lowatmospheric pressure due to the fact that edge 2908 passes edge 2910without the hindrance of cord 2954. Hence, to cause edge 2908 to passedge 2910, expansion force need only overcome the stiffness of thematerial comprising flow-reducing implant 2900. In an exemplaryembodiment, a pressure of between 3-4 atmospheres (optionally 3atmospheres or less or 4 atmospheres or more), causes expansion of wallthe lumen through flow-reducing implant 2900.

In an exemplary embodiment of the present invention, flow-reducingimplant 2900 comprises cord 2954 passing through slits 2924 and a cord2964 passing through slots 2988. Alternatively or additionally,flow-reducing implant 2900 comprises three or more cords: 2954, 2964 ateither end and a cord 2974 passing through slots 2926 substantially inthe middle of flow-reducing implant 2900.

Cords 2954, 2964 and/or 2974 serve to maintain the shape and/orappropriate lumen diameter following installation. To expand the lumenthrough flow-reducing implant 2900, balloon catheter 1000 is used toexpand and/or sever cords 2954, 2964 and/or 2974. Alternatively oradditionally, sever cords 2954, 2964 and/or 2974 are biodissolvable,dissolving in the environment of coronary sinus 2110.

It should be noted that when implant 2900 is deployed, the final shapeis that of a cone, the relative lengths 2948, 2938 and 2928 of the slits2946, 2936 (and 2934) and 2926, respectively, generally define thegeometry of the expanded device. As shown, the cone shape is convex.However, other shapes, for example, concave may be provided instead.Also shown in this embodiment is that the slits are staggered, so thatthe expansion will be generally distributed over the surface of theimplant.

While the above has been described for use in coronary veins, a flowreducing implant with similar design may also be used in other veins,for example, popliteal, tibial or saphenous veins. In an exemplaryembodiment of the invention, described in greater detail below, one ormore flow reducing implants are implanted in popliteal veins, toincrease back-pressure and possibly enhance tissue perfusion pressureand/or redistribute blood flow in the leg. It is expected that poolingwill not occur due to the existence of alternative drainage paths in theleg. Multiple insertions of flow reducing implants may be used to treatand/or hide varicose veins.

Within the closed facial compartments of the lower limb, a plurality ofthin-walled, valved venae comitantes are subjected to intermittentpressure both at rest and during exercise. The pulsation of the adjacentarteries help to move the blood up the limb. Also, the contractions ofthe large muscles within the compartments during exercise compress thesedeeply placed veins and force the blood up the limb. The superficialsaphenous veins, except near their termination, lie within thesuperficial fascia and are not subject to these compression forces. Thevalves in the perforating veins, which interconnect deep and surfaceveins, prevent the high-pressure venous blood from being forced outwardinto the low-pressure superficial veins. Moreover, as the muscles withinthe closed facial compartments relax, venous blood is sucked from thesuperficial into the deep veins. Lower limb venous pressure increases todependency, stimulating a local sympathetic axon reflex, which triggersprecapillary and arteriolar vasoconstriction. The resulting decrease inarterial calf inflow, known as the venoarterial response (VAR), isimpaired in critical ischemia. The median VAR was found to besignificantly lower in patients with stable claudication than in normalsubjects or patients following successful revascularization (29.1 versus59.5 and 63.9 percent respectively). Thus, patients with claudicationapparently have a significant impairment of orthostatic sympatheticautoregulation. It should be mentioned that neovascularization isconsidered an important cause of venous reflux recurrences afterligation of foot veins. The pathogenesis of this phenomenon is so farobscure. It has been hypothesized that a hemodynamic factor could be thetrigger initiating the process of neovascularization. In an exemplaryembodiment of the invention, such a factor is provided in a form ofincreased pressure caused by reduction in vein diameter.

In an exemplary embodiment of the invention, the implantation of flowreducing implants in the veins is used to treat diabetic foot syndromeand/or varicose veins. In an exemplary embodiment of the invention, theblood vessels treated include a lower limb vein, for example asuperficial vein such as the great or small saphenous veins or theirtributaries, or a limb deep vein such as the anterior and posteriortibial or popliteal veins, or a limb perforating vein, such as those inthe region of the ankle and the medial side of the lower part of theleg. The degree of reducing and/or size of the flow reducing implant maybe the same as used for the coronary sinus and/or be adapted to fit theparticular vein being treated.

In an exemplary embodiment of the invention, the implantation procedureis as described above for the coronary sinus, except, of course, thatthe flow reducing implant is conveyed to a leg vein, rather than to thecoronary sinus, for example, via a femoral vein. Desirably, the flowreducing implant is implanted using a trans-vascular approach, forexample, from the venous system. In an exemplary embodiment of theinvention, the delivery system is inserted through a femoral vein to adeep lower limb vein, such as the popliteal vein or tibial vein. Once inthe deep foot vein, the delivery system is guided (e.g., through a sharpbend) to the vein. Alternatively, for example, an open surgery approachmay be used instead.

In a particular exemplary embodiment of the invention, a flow reducingimplant is placed in a tibial vein and has a narrowing significantenough to encourage the formation of collateral circulation. It ishypothesized that collateral circulation is caused by an increase invenous blood pressure, which, in turn, increases the pressure in thecapillaries and/or causes retro-flow in the capillaries and/or causesdrainage of the capillaries. Alternative or additional hypotheses thatare optionally used to select the constrictive effect of flow reducingimplant include:

(a) the flow reducing implant increases the pressure in the footcapillaries, thus increasing perfusion duration;

(b) an increase in resistance of the venous system causes redistributionof blood flow in the ischemic foot; and

(c) increasing the arterial diastolic pressure (by restricting venousdrainage) activates the sympathetic auto-regulation mechanism.

It should be noted that the selection of flow reducing implant may bemade to achieve one or more of the above suggested effects, optionallyto a desired degree and/or taking into account safety issues, such asallowing some drainage and maximum pressure allowed by the venousdrainage system. These effects may be determined using variousmeasurements, such as a pressure sensor on the implanting catheter.

In an exemplary embodiment of the invention, the selection of the flowreducing implant depends on one or more of:

(a) The lower limb vein length and diameter (e.g., to obtain a matchingflow reducing implant geometry);

(b) Desired increase in the lower limb deep venous pressure before flowreducing implant, optionally including a maximum allowed pressure, forexample, 50 mm Hg at which a peripheral vein expected to be damagedand/or fail (e.g., to decide what narrowing to select);

(c) Desired narrowing (e.g., to decide what narrowing to select);

(d) Desired later further narrowing (e.g., to decide on flow reducingimplant type);

(e) Resistance of the lower limb vein wall (e.g., how elastic or stiffshould flow reducing implant be and/or what inflation pressure to use);

(f) Desired redistribution of lower limb blood flow; and/or

(g) Desired retro-flow of blood in lower limb arteries and/or veins.

In an exemplary embodiment of the invention, the venous location of theflow reducing implant is selected to match various limb conditions, suchas arterial blockage, alternatively or additionally to selecting thereducing diameter for each such flow reducing implant. Alternatively oradditionally, the location(s) of implantation are selected to achieve adesired redistribution of lower limb artery pressures and/or blood flow,for example, to increase perfusion of ischemic or hibernating portionsof the foot.

In an exemplary embodiment of the invention, the flow reducing implantimplantation is combined with an arterial treatment, such as PCTA,stenosis removal (e.g., laser ablation) and/or stenting. The arterialtreatment may be applied, for example, before, during or after thevenous treatment, possibly during a same use of catheterizationfacilities. Doppler measurements are optionally used to asses legperfusion. Alternatively or additionally, other perfusion and/or flowassessment methods may be used. Alternatively or additionally, anangiographic mapping is used before, during or after the procedure, forexample to assist in determining what size flow reducing implant to useand/or a test obstruction of the lower limb vein. Such mapping may, forexample, assist in determining a desired narrowing dimension of the flowreducing implant that will achieve a desired pressure increase and/or todetect possible side effects in the patient of such a pressure increase.

It is expected that one or more of the following effects is detected (atonce and possibly to a greater extent after some delay): retrogradeincrease in the lower limb venous pressure, with a possible associatedretrograde flow and/or improvement of perfusion in some ischemic areas.

It is expected that in some cases after a few weeks, the lower limbperfusion will increase and redistribution of blood flow will improve,even beyond the immediate result of the insertion of the flow reducingimplant. Possibly, the autonomic auto-regulation mechanism of the venousflow will be reset and/or restart. After a few months, revascularizationis expected, in some cases, to be well established, and significantlyimprove the clinical picture.

In another example, the flow reducing implant can be adapted to matchother ducts or conduits in the body, for example, with respect to size,length, degree of narrowing, degree of elasticity and form of contactwith the conduit walls.

In an alternative set of applications a flow reducing implant is used toreduce blood flow to a growth, for example a cancerous growth or othertumors.

A first example in the treatment of tumors is the uterus. The myometrium(inner lining of uterus) gives rise to a common tumor, a leiomyoma,which is a major source of abnormal uterine bleeding and a majorindication for hysterectomy. The endometrial cavity is often the site ofhyperplasia and neoplasia.

Uterine Leiomyomas, commonly known as fibroids or myomas, arewell-circumscribed, benign tumors arising from the smooth muscle of themyometrium. They are composed of smooth muscle and extracellular matrix.Leiomyomas are the most common solid pelvic tumors in women. These areclinically apparent in 20% to 25% of women during the reproductiveyears, but careful pathologic inspection of the uterus reveals that theyare present in more than 80% of women. Leiomyomas are characterized bytheir location in the uterus. Subserosal leiomyomas are located justunder the uterine serosa and may be attached to the corpus by a narrowor a broad base. Intramural leiomyomas are found predominantly withinthe thick myometrium but may distort the cavity or cause an irregularexternal uterine contour. Submucous leiomyomas are located just underthe uterine mucosa (endometrium). A known treatment is Uterine arteryembolization in which small bubbles are freed in a supply vessel (e.g.,a Uterine artery), causing embolisms in capillaries of the leiomyoma.

Interestingly, because the uterus receives branches from uterine andovarian arteries, the uterus has a dual blood supply. The uterine arteryis derived from the hypogastric anterior trunk. It crosses over theureter at the level of the internal os of the cervix and divides intoascending and descending limbs. The ascending limb runs tortuouslyupward, between the leaves of the broad ligament, and supplieshorizontal anterior and posterior branches to the cervix and the corpus.The descending branch of the uterine artery turns inferiorly andsupplies the vagina from the lateral aspect. It anastomoses freely withthe vaginal artery along its course. The ovarian arterial supply alsohas branches that anastomose with the ascending limb of the uterineartery.

In accordance with an exemplary embodiment of the invention, a leiomyomais distinguished from healthy tissue by its degree of collateralvasculature and/or its sensitivity to ischemia.

In an exemplary embodiment of the invention, uterine fibroid tumors aretreated by implanting a flow reducing implant in selected uterinearteries, thus causing a reduction of the arterial blood supply of theuterine fibroid tumor, leading to ischemia and gradual necrosis of thetumor.

In an exemplary embodiment of the invention, the procedure is asfollows. With the patient under mild intravenous sedation and localanesthesia, a small angiographic catheter is introduced into the femoralartery and guided into the left uterine artery. Arteriography isperformed, determining the arteries diameter. A flow reducing implant isthen inserted into the artery, causing a narrowing of its diameter. Theprocess is optionally repeated in the right uterine artery. The flowreducing implant reduces arterial blood flow through the uterinearteries and causing ischemic necrosis. Normal myometrium is possiblyunharmed because multiple collateral arteries supply it. After the rightand left uterine arteries are catheterized, the catheter is removed, andthe patient optionally undergoes standard post-arteriographic monitoringand recovery. Optionally, the narrowed section reduces the vesselcross-section by 30%, 50%, 80%, 90% or any other lower, larger orintermediate amount, or even completely occludes the vessel. Forexample, the narrowed section may have an inner diameter of 0.3 mm, 0.5mm, 1 mm or any larger, smaller or intermediate size.

As with the coronary application described above, a uterine procedurecan be minimally invasive (e.g., using a laparoscope or a catheter), orbe applied while performing other surgery.

Another application is treating cancer. In a known treatment of livercancer, a viscous material is injected into a supply vessel of livercancer, then a chemical poison is injected and then the vessel issealed. However, the use of viscous material has various associateddangers, such as causing embolism in the brain and lungs.

In an exemplary embodiment of the invention, a flow reducing implant isused for treating cancer, especially cancer of the liver, for example,isolated liver metastases and for hepatocellular carcinoma and/or othertumors including HCC, colorectal, neuroendocrine, leiomyosarcoma, andmelanoma metastases.

In an exemplary embodiment of the invention, malignant tumors aretreated by implanting a flow reducing implant in selected arteries thatsupply the malignant tumors, thus causing a significant reduction ofarterial blood to the tumor, leading to tumor-cell hypoxia. This resultsin a controlled tumor regional ischemia and infarct and subsequentnecrosis of tumors in the infarcted region. Optionally, various chemicaltreatments, such as known in the art are used as well.

The liver is apparently especially amenable to this approach, due to thedistinct lobular anatomy of the liver. Another potential factor is theexistence of two independent blood supplies to the liver. A furtherpotential factor is the ability of healthy hepatic tissue to compensatefor tissue mass lost.

In an exemplary embodiment of the invention, the procedure is asfollows. Under local anesthesia and mild sedation, a superselectivecatheter is inserted via a selected artery and threaded into the desiredartery supplying the tumor, for example into the hepatic artery.Angiography is then performed to delineate the organ vasculature andperforming various measurements, such as determining the diameter of theartery and measuring the required flow reducing implant diameter,followed by placement of the selected flow reducing implant. Anangiographic study allows clear visualization of the hypervasculartumor, which is further studied by means of superselectivecatheterization. After the flow reducing implant has been placed, andfurther measurements have optionally been performed, such as pressurestudies and another angiographic visualization, the catheter is removed,and the patient undergoes standard post-arteriographic monitoring andrecovery.

In an exemplary embodiment of the invention, the method described may beused concurrently with an intraarterial infusion of antineoplasticagents mixed, for example, with iodized oil (Lipiodol (R)), which hasbeen extensively used in the treatment of large HCC tumors, or combinedwith PEI (Percutaneous ethanol injection). It is expected that alcoholdiffusion be easier after the occurrence of the hypoxic/necrotic changesproduced by the implant, thus allowing the intranodular injection oflarger amounts of ethanol. Moreover, after arterial embolization, thenormal washout of the injected ethanol is more difficult in the tumorousarea, resulting in potential longer retention of the substance. Variouspharmaceuticals may be discharged by the flow reducing implant itself,as known, for example in the art of stents. For example, the flowreducing implant may be coated with various pharmaceuticals or the flowreducing implant may include a dissolving portion or a reservoir.

It will be appreciated that the above described methods of deploying aflow reducing implant may be varied in many ways, including, changingthe order of acts, which acts are performed more often and which lessoften, the type and order of tools used and/or the particular timingsequences used. Further, the location of various elements may beswitched, without exceeding the sprit of the disclosure. In addition, amultiplicity of features, both of methods and of implants have beendescribed. It should be appreciated that different features may becombined in different ways. In particular, not all the features shownabove in a particular embodiment are necessary in every similarexemplary embodiment of the invention. Further, combinations of featuresfrom different embodiments into a single embodiment or a single featureare also considered to be within the scope of some exemplary embodimentsof the invention. In addition, some of the features of the inventiondescribed herein may be adapted for use with prior art devices, inaccordance with other exemplary embodiments of the invention. Theparticular geometric forms and measurements used to illustrate theinvention should not be considered limiting the invention in itsbroadest aspect to only those forms. Although some limitations aredescribed only as method or apparatus limitations, the scope of theinvention also includes apparatus designed to carry out the methods andmethods of using the apparatus.

Also within the scope of the invention are surgical kits, for example,kits that include sets of delivery systems and flow reducing implants.Optionally, such kits also include instructions for use. Measurementsare provided to serve only as exemplary measurements for particularcases, the exact measurements applied will vary depending on theapplication. When used in the following claims, the terms “comprises”,“comprising”, “includes”, “including” or the like means “including butnot limited to”.

It will be appreciated by a person skilled in the art that the presentinvention is not limited by what has thus far been described. Rather,the scope of the present invention is limited only by the followingclaims.

The invention claimed is:
 1. A method of treating abnormal growth in thebody, comprising: determining a source blood vessel for the abnormalgrowth; inserting a flow reducing implant into the source blood vessel,said flow reducing implant including a flared section for contacting ablood vessel wall and a narrowed section defining a flow passage; andreducing blood flow through the source blood vessel with the flowreducing implant and without completely occluding the source bloodvessel, thereby allowing blood flow through the source blood vesselafter permanent implantation of the flow reducing implant, and whereinthe reduced blood flow causes ischemia and necrosis of the abnormalgrowth.
 2. A method according to claim 1, wherein said growth is extantin an organ that is fed from multiple source blood vessels.
 3. A methodaccording to claim 1, wherein said growth is fed by a single sourceblood vessel.
 4. A method according to claim 1, wherein said growthcomprises a leiomyoma.
 5. A method according to claim 1, wherein saidgrowth comprises a malignant tumor.
 6. A method according to claim 5,wherein said tumor is a liver tumor.
 7. A method according to claim 5,wherein said tumor is an encapsulated tumor.
 8. A method according toclaim 1, further comprising narrowing the narrowed section afterinsertion of the flow reducing implant to further reduce blood flowtherethrough.
 9. A method according to claim 1, wherein said flowreducing implant is defined by a sheet material with slots, a width ofsaid slots varying over said flow reducing implant to control anexpanded geometry of said flow reducing implant.
 10. A method of using aflow reducing implant for treatment of an abnormal growth in the bodycomprising: determining a source blood vessel for the abnormal growth;inserting the flow reducing implant into the source blood vessel, saidflow reducing implant including a flared section for contacting a bloodvessel wall and a narrowed section defining a flow passage; and reducingblood flow through the source blood vessel with the flow reducingimplant and without completely occluding the source blood vessel,thereby allowing blood flow through the source blood vessel afterpermanent implantation of the flow reducing implant, and wherein thereduced blood flow causes ischemia and necrosis of the abnormal growth.11. A method according to claim 10, wherein said flow reducing implantfurther includes an anchor tab that lies generally in a plane of saidflared section, the method further comprising anchoring the flowreducing implant to the source blood vessel with the anchor tab.